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GLOSSARY

Our comprehensive glossary is available to assist in your understanding of the S'COOL lesson plan vocabulary words. Please select the first letter of the word you wish to check for a definition and further information.

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All definitions

A
Active Remote Sensing:
An instrument, for example a radar or lidar, sends out a beam of energy to probe the thing it wants to sense; then measures the amount of energy that is reflected (bounced) back to a detector. In space, active sensors have only been used relatively recently as they involve additional technical challenges.  
A
agriculture:
The science of production of foods through farming or other means of growing a product for human consumption and use.  
A
air mass:
a body of air that has relatively uniform temperature and humidity based on the surface characteristics of its source region.   Continental polar air mass formed over Canada
Image courtesy University of Illinois WW2010 Project
A
air pressure:
the weight of the column of the atmosphere above a surface. On average, the atmospheric pressure at sea level is 1013.25 millibars (mb), but it can be relatively higher or lower than this value based on air temperature and humidity. Changes in atmospheric pressure at a given location often indicate changing weather.   More about atmospheric pressure Explanation of atmospheric pressure
Image courtesy University of Illinois WW2010 Project
A
albedo:
a measure of reflectivity; the planetary albedo of the Earth averages about 0.31, meaning that on average about 31 percent of the light from the Sun is reflected back to space. The value at any given time is dependent on cloud cover and ground cover (snow, ice).  
A
altitude:
the vertical distance or height measured from sea level..  
A
altocumulus:
A mid-level cloud that has individual cloud elements or heaps of cloud..   S'COOL On-line cloud chart Altocumulus during Texas Spring
Image courtesy Mandy Khaiyer
A
altostratus:
A mid-level cloud that is featureless and formless.   S'COOL On-line cloud chart Altostratus in Southeastern Virginia
Image courtesy S'COOL Project
A
anemometer:
Instrument used to measure wind speed.   A cup anemometer
Image courtesy NASA
A
angle bisector:
The line that divides an angle into two equal angles of half the size.   Image of Angle Bisector
A
Atmosphere:
the mixture of gases that surrounds the Earth and some other planets. The concentrations of the gaseous constituents of Earth's at mosphere are determined by biogeochemical processes, including manmade effects..   Image of the top layers of the earth's atmosphere leading to space
Image courtesy of Earth Sciences and Image Analysis Laboratory,NASA Johnson Space Center
B
bar graph:
a style of graph that uses a verticle or horizontal rectangle to represent a certain set of data that is being shown on the plot.  
B
barometer:
an instrument that measures air pressure.   Barometer Basics photo of barometer
B
Beaufort Wind Scale:
Named after Sir Francis Beaufort and established in 1806, the Beaufort Wind Scale initially classified wind speed into 13 classes (zero to 12) based on mariner conditions. Later in history the scale was slightly altered to improve usefulness for meteorologists. Today we can relate the Beaufort Wind Scale to the Saffir-Simpson Hurricane Scale (category 1 on the Hurricane scale is equivalent to a 12 on the Beaufort scale)..   NOAA table for Beaufort Wind Scale
B
blizzard:
a severe storm with defining characteristics of very low temperatures, severe winds, as well as large amounts of blowing snow in the area of the storm.  
C
calculate:
to reach a mathematical conclusion.  
C
carbon emissions:
carbon substances that are released into the atmosphere due to human activities. These substances are pollutants.  
C
carbon footprint:
A visual representation of the effects of your lifestyle on the environment. It literally is the impact of human actions or lifestyles on the environment, in terms of greenhouse gas emissions measured in units of carbon dioxide..  
C
cell:
1. an air mass that contains both up and down drafts, however it acts as one large object and is the smallest part of the storm creation process. 2. a box defined by a lettered column and a numbered row, for example, B2. This is where text and number values are entered into a spreadsheet.  
C
Celsius:
A scale for the measurement of temperature named after Anders Celsius, a Swedish astronomer, who invented it. Water freezes at 0 degrees C and boils at 100 degrees C.   Temperature conversion tool Fahrenheit, Celsius and Kelvin temperature scales
Image courtesy NASAexplores
C
centimeter:
A unit measuring distance or height. It is used as a unit for precipitable water in the LAS. This is the height of the layer of water that would exist if all the water vapor in the atmospheric column were condensed to liquid at the Earth's surface..  
C
CERES:
The Clouds and the Earth'Radiant Energy System is one of the scientific satellite instruments developed for NASA's Earth Observing System (EOS)..   The CERES Web Site Reflected Solar Radiation for July 2000
Image courtesy CERES Science Team
C
cirrocumulus:
clouds are high-altitude cloud, usually occurring at 16,000-40,000 feet. Like other cumulus clouds, cirrocumulus clouds signify convection. Unlike other cirrus clouds, cirrocumulus include liquid water droplets, although these are in a supercooled state. Ice crystals are also present, and typically, the ice crystals cause the supercooled water drops in the cloud to rapidly freeze, transforming the cirrocumulus into cirrostratus. This process can also produce precipitation in the form of a virga consisting of ice or snow. Thus cirrocumulus clouds are usually short-lived..   Cloud Classification Chart from the S'COOL Project large-celled cirrocumulus
Image courtesy Jeff Caplan, NASA Photographer in 1997.
C
cirrostratus:
thin, sheetlike high clouds that often cover the entire sky, but allow the Sun and Moon to shine through.   Cloud Classification Chart from the S'COOL Project
C
cirrus:
high feathery clouds that usually mean a change in weather is on the way.   Cloud Classification Chart from the S'COOL Project Wispy Cirrus
Image courtesy Lin Chambers, August, 2002
C
climate:
general weather patterns experienced in a place over a long period of time.  
C
Climate Change:
Includes global warming and everything else that increasing greenhouse gas amounts will affect.   Global Warming vs. Climate Change
C
cloud:
collections of water (in liquid or ice phase) in the atmosphere that are often classified by their shape and height..   Cloud Classification Chart from the S'COOL Project photo of cloud
Image courtesy NASA S'COOL Project
C
cloud coverage:
Cloud coverage, also called cloud fraction, or cloud cover, describes the amount of cloud in the sky. It can be measured as a percentage (0-100) or as a fraction (0-1.0).   Observing Cloud Cover
C
cloud fraction:
See cloud coverage.  
C
cloud opacity:
a parameter that characterizes the reduction of light or energy through a cloud due to interactions with its water, ice or particle content. See definition for optical depth.   Observing Cloud Visual Opacity
C
cloud temperature:
The cloud temperature is, as it sounds, the temperature of a cloud. However, what this means exactly depends on how the measurement is made. Most of the time we do not put a thermometer in the cloud, but instead determine this by remote sensing. And most clouds are not at a single temperature, but are generally colder at the top and warmer at the bottom. The temperature measured by remote sensing is often called a cloud effective temperature. It measures the temperature of the cloud mass within about 1 optical depth of the edge (where optical depth varies with wavelength, so that the measured temperature depends on the sensor being used, at least to some extent). Measurements made from orbit, then, will generally measure a lower temperature than those made from the ground (unless the cloud is thin).   Clouds in Infrared Imagery
C
cloud types:
typically a list of the various kinds of clouds. These cloud types are derived from a Latin root word. Each of the various names of the cloud types corresponds to what it looks like and its relative height in the atmosphere.   S'COOL Cloud Chart
C
cold front:
The boundary between a cold air mass and a warm air mass, in which the cold air mass pushes under the warmer air mass. A cold front tends to move through a region more quickly than a warm front, and is usually accompanied by colder weather.   tutorial on cold fronts Cloud wall associated with fast moving cold front
Image courtesy NOAA - cloud wall associated with fast moving cold front
C
column:
This is a vertical feature that is used to describe an objects orientation. In an excel spreadsheet these are the up and down features with an alphabetical listing on the top of the page.  
C
concept mapping:
This is a visual representation of words that show their relationship to a central theme or event.   concept map example
C
condensation:
the phase change of water from vapor to liquid by cooling, releasing latent heat energy to the atmosphere, or, when water changes from a gas state to a liquid state.  
C
condensation nuclei:
small particles or aerosols which water vapor attaches to begin the condensation process. Theses particles include but are not limited to dust particulates, sea salt, sulfur and other like particulates. As the temperature decreases to the condensation point, the water vapor in the atmosphere attaches to these particulates and begins the process of cloud formation..  
C
contrail:
condensation trail; cloud formed due to the exhaust of jet aircraft.   GLOBE Contrail Education Web Site Image of persistent contrails, newer (left) to older (right)
Image courtesy Carol Clark, Oregon
C
convection:
the transfer of heat energy vertically through a medium. In the atmosphere, convection may be seen visibly by cloud formation and thunderstorm development.  
C
conversions:
mathematical equations used to convert from one unit to another, such as with temperature. F=1.8C+32 and C=(F-32)x(5/9), these are equations are used to convert from one unit to the next.  
C
convert:
to mathematically change units of one measuring or calculating system into units of another.  
C
cumulonimbus:
a type of cloud that is tall, dense, and associated with thunderstorms and other intense weather.  
C
cumulus:
a puffy white cloud often described as "puffy" or "cotton-like" in appearance, cumulus clouds may appear alone, in lines, or in clusters.   Fair Weather Cumulus
Image courtesy Photo by Lin Chambers, July 2003
D
data:
a collection of information that can be used to support a scientific process. Different types of data include quantitative and qualitative data.   example of data types
D
database:
a type of computer program used for consolidating and organizing a collection of data for quick access and use in many different ways.  
D
degree:
a standard unit of measure for several purposes to include temperature on a scale such as Celsius, Fahrenheit or Kelvin, latitude or longitude to locate or designate places on Earth, and planar angles equal to a 360th of a circle.   Fahrenheit, Celsius and Kelvin temperature scales
Image courtesy NASAexplores
D
descend:
the process of moving from a higher to a lower location. A climber is descending down a mountain when he or she is going from the top to the bottom.  
D
dew:
tiny water drops that form when water vapor condenses onto an object (ground, grass, etc.).   Dew on some leaves
D
dew point:
the temperature to which an air mass must be cooled in order for the air mass to become saturated (relative humidity equals 100 percent), assuming constant pressure and moisture content. Additional moisture would condense into water droplets.  
D
diameter:
a line that goes across the center point of a circle and whose endpoints lie on the perimeter of the circle.  
D
dichotomous key:
a written list or series of steps that will eventually lead you to the positive identification of an object, e.g. species of animal or cloud type.   Dichotomous key example
D
direct observation:
This is when scientists themselves make notes and observations about a particular object. As opposed to relying on someone elses data to draw conclusions.  
D
download:
a process by which information is transferred from one computer to another.  
D
droplets:
collection of separate small amounts of liquid.  
D
dust storm:
a situation in which the wind speed is high enough to remove particles of unconsolidated material and put it into the air in quantities that decrease visibility. This is most common in areas with a low humidity throughout the year.   Phoenix dust storm
E
electrical charge:
the characteristic of matter that is responsible for electric forces, expressed as positive or negative.  
E
energy budget:
The Earth's energy budget describes the various kinds and amounts of energy that enter and leave the Earth system. It includes both radiative components (light and heat), that can be measured by CERES, and other components like conduction, convection, and evaporation which also transport heat from Earth's surface. On average, and over the long term, there is a balance at the top of the atmosphere. The amount of energy coming in (from the Sun) is the same as the amount going out (from reflection of sunlight and from emission of heat).   Earth's Energy Budget Graphic Earth Radiation Budget Illustration
E
entry bar:
Location in a web browser where the url is entered so that a web page can be accessed.  
E
evaporation:
the process where liquid water is converted to water vapor (gaseous state). The air above the evaporating surface must be unsaturated for evaporation to occur (relative humidity less than 100 percent).   Photo of evaporation
Image courtesy NASA
F
fact:
something that has repeatedly been shown to be true and that can be recreated.  
F
Fahrenheit:
A scale for the measurement of temperature named after Gabriel Daniel Fahrenheit, a German physicist who invented the mercury thermometer and this scale. Water freezes at 32 degrees F and boils at 212 degrees F.   Temperature conversion tool Fahrenheit, Celsius and Kelvin temperature scales
Image courtesy NASAexplores
F
fiction:
literary work that is based on ones imagination. These works may have truthful elements, but the vast majority of the book is not based on fact.  
F
field:
1. the location in a web page or spread sheet in which the user must place certain information. 2. a plot of land that is void of trees and other tall objects, often used to plant a crop. (i.e. the students made cloud observations from the edge of the corn field.) 3. An area in which a person has a large quantity of knowledge. (i.e. Dr. Smiths field of experience is geology).  
F
fog:
A visible gathering of water droplets suspended in the air near the Earth's surface.   Fog Image
Image courtesy Kate (age 9) of St. James School in Falls Church, Virginia
F
folk lore:
stories that are often not written down on paper for others to read for reference. This is something that is told through stories or passed down in the form of pictures that relate to a particular culture.  
F
forecast:
making a prediction before something is to happen. For example, in meteorology a model is used to predict what the weather will be like at a certain time and location.  
F
formula:
(a) a plan or method, written in words or symbols, that describes a procedure for doing something. An example is using K = C + 273 to convert from Kelvin temperature to Celsius temperature; (b) grouping of certain items that, when combined, form a new substance. An example is combining two hydrogen atoms to one oxygen atom to form a water molecule..  
F
frequency distribution:
an arrangement of data in a graphical form that allows someone to see how often a certain event happened.  
F
front:
the boundary between two distinct air masses which differ in temperature and humidity. There are different types of fronts such as cold front, warm front, stationary front, and occluded front..   Information about weather and fronts from World Book at NASA
F
frost:
tiny ice crystals that form when water vapor freezes onto an object (ground, grass, window).  
G
Geostationary Orbits:
A geostationary (GEO=geosynchronous) orbit is one in which the satellite is always in the same position with respect to the rotating Earth. The satellite orbits at an elevation of approximately 35,790 km because that produces an orbital period (time for one orbit) equal to the period of rotation of the Earth (23 hrs, 56 mins, 4.09 secs). By orbiting at the same rate, in the same direction as Earth, the satellite appears stationary (synchronous with respect to the rotation of the Earth). Geostationary satellites provide a "big picture" view, enabling coverage of weather events. This is especially useful for monitoring severe local storms and tropical cyclones. Because a geostationary orbit must be in the same plane as the Earth's rotation, that is the equatorial plane, it provides distorted images of the polar regions with poor spatial resolution. .   For more information on orbits.
G
Global Warming:
Describes the average global surface temperature increase from human emissions of greenhouse gases.   Global Warming vs. Climate Change
G
graph:
A visual representation of a particular data set.   Bar Graph
Image courtesy Nasa S'COOL Project
G
gravity:
a physical force that is responsible for the force of attraction between any two bodies that have mass. The Earth's gravity is what keeps us from floating into space.  
G
Green:
To become conscious of how your actions affect the environment and to make lifestyle decisions with the environment in mind.  
G
Greenwich Mean Time:
Standard time at longitude = 0 (the longitude line which goes through Greenwich, England) which is used as a standard around the world to assist in synchronizing data collection..   Look here to figure out the time offset from UT to your time zone.
G
ground truth:
an observation where a person on the ground (or sometimes in an airplane) makes a measurement of the same event or quantity that a satellite is trying to measure, at the same time the satellite is measuring it. The two measurements are then compared to help evaluate how well the satellite instrument is performing.  
H
hail:
precipitation in the form of ice pellets that are a result of upward moving air currents that pull the liquid rain upward, then freeze the rain due to the decreasing temperature with higher altitude.  
H
halo:
a ring that appears around a source of light such as the sun, moon or even a street light.   Image of halo
H
heat:
The energy transferred from one body or system to another as a result of a difference in temperature.  
H
high clouds:
group of clouds that includes Cirrocumulus, Cirrus and Cirrostratus, these clouds are at an approximate height of 6.25 to 8.00 Km above the ground.   Cloud Types at Low, Mid and High Levels
H
high pressure:
having an atmospheric reading in millibars higher than 1013.25. (standard sea-level atmospheric pressure is 1013.25mb).  
H
high pressure area:
a particular region in which the atmospheric pressure is elevated above standard conditions. In this area the wind moves in an outward direction and clockwise around a center in the northern hemisphere, and counter-clockwise in the southern hemisphere. Areas with high pressure are characterized by nice weather.  
H
histogram:
a particular type of bar graph that depicts a frequency distribution of a data set.  
H
hue:
particular shade or tint of color.  
H
humidity:
the amount of moisture (water vapor) in the air.  
H
hurricane:
a giant swirling storm characterized by a low pressure center and numerous thunderstorms that produce strong winds and flooding rain.   Hurricane Floyd - Sept. 14, 1999
Image courtesy NOAA GOES Satellite - NASA Goddard Space Flight Center
H
hygrometer:
an instrument that measures the amount of humidity in the air.   picture of hygrometer
H
hypothesis:
one of the steps to the scientific method that is an intended proposal. This can be described as an educated guess that is often in the form of an if then statement. (i.e if the temperature increases the ice will melt at a greater rate.).  
I
Imager:
Most instruments that orbit the Earth can produce pictures, but an imager is an instrument designed specifically to do that. Typically it has more spatial resolution than other instruments (that is, it can see smaller features on the surface), and it also collects energy in only a small part of the electromagnetic spectrum. Many imagers have channels in red, green, and blue light, which can be used to reconstruct true color imagery of Earth - as a person would see it. Many also have some other channels, which can be used to produce false color images that bring out specific features of interest. For more information, see an introduction to remote sensing..   MODIS Instrument
I
inches:
a unit of measurement that is most often used in the United States. An inch is equal to one twelfth of a foot it is also equal to 2.54 centimeters.  
I
Inclined Orbits:
Inclined orbits fall between those above. They have an inclination between 0 degrees (equatorial orbit) and 90 degrees (polar orbit). These orbits may be determined by the region on Earth that is of most interest (i.e., an instrument to study the tropics may be best put on a low inclination satellite), or by the latitude of the launch site. The orbital altitude of these satellites is generally on the order of a few hundred km, so the orbital period is on the order of a few hours. These satellites are not sun-synchronous, however, so they will view a place on Earth at varying times.   For more information on orbits.
I
indirect observation:
This is a unit of measurement that is most often used in the United States. An inch is equal to one twelfth of a foot; it is also equal to 2.54 centimeters.  
I
inflate:
force a gas into a hollow container, such as a balloon, to increase its size.  
K
Kelvin:
An absolute temperature scale invented in the 1800's by William Thompson, Lord Kelvin. It places the zero point of the scale at absolute zero, the temperature which scientists believe is the lowest possible. All molecular motion would stop there. A Kelvin degree is the same size as a Celsius degree, so the two scales simply have a constant offset.   Temperature conversion tool Fahrenheit, Celsius and Kelvin temperature scales
Image courtesy NASAexplores
K
kilometer:
A kilometer is a unit of measurement within the Metric System. Metric units are defined in powers of ten. 1 kilometer is equivalent to 1,000 meters or 0.62 miles. It is a common measurement of distance..  
L
latitude:
a measure which identifies the north - south location of a point on the Earth. It is the angle between the line connecting a point on the Earth and the Earth'center, and the equatorial plane of the Earth. There are three ways to express latitude. You may be most familiar with 0-90 North and 0-90 South. In the computer era this became -90 to +90, where -45 equivalent to 45 South. The third method is less familiar and is called the colatitude. Colatitude is 0 at the north pole, 90 at the equator, and 180 at the south pole. So, 45 South is equivalent to a colatitude of 135..   diagram showing latitude
L
Lifting Condensation Level:
The level in the atmosphere at which a parcel of moist air that rises as it is warmed will reach 100% relative humidity and cloud droplets will begin to form.  
L
lightning:
a giant electric spark created during a thunderstorm.   Double lightning
L
line graph:
a particular type of graph that uses lines to show a trend in a data set.   Image of Line Graph
Image courtesy NASA S\'COOL Project
L
Local Daylight Saving Time:
The local standard time, plus an hour. This change is made in some parts of the world during summer months so as to cause the day's activities to begin earlier, with the goal of providing more time for leisure and recreation..  
L
Local Solar Time:
The local time where you are using the sun as a reference. Noon would be when the Sun is at its highest point. A sundial would help you measure this..  
L
Local Standard Time:
The time established for a region by law, or general use - it's the time you see on a correctly set clock, if you're not in daylight savings time (summer).  
L
longitude:
a measure which identifies the east - west location of a point on the Earth. It is the angular distance along a line of latitude from the Greenwich Meridian - a reference longitude set to be zero degrees. There are three equivalent ways to express longitude, and scientists tend to use them interchangeably. You may be most familiar with longitude as 0-180 East, and 0-180 West. It can also be expressed as 0-360 East, or just 0-360. In that case, 270 East is equivalent to 90 West. The third system arose in the computer era, when carrying both a number (0-180) and a character (East or West) was inconvenient. The new convention of -180 to +180 was then developed. In this case,-90 is equivalent to 90 West.   diagram showing longitude
L
low clouds:
Cloud types that have a maximum approximate height of 2 Km. These include cumulus, nimbostratus, fog, stratocumulus as well as cumulonimbus clouds.   Cloud Types at Low, Mid and High Levels
L
low pressure:
a pressure reading in millibars that is less than the standard sea level reading of 1013.25 mb.  
L
low pressure area:
a particular region in which the average atmospheric pressure is lower than the standard sea level pressure of 1013.25 mb.  
M
mean:
the mathematical average of a set of numbers that are added and divided by the total number of figures.  
M
median:
The middle number in a set of data.  
M
meteorologist:
a scientist that studies the weather.  
M
meteorology:
a field of earth science that deals with the phenomenon of weather in the atmosphere.  
M
mid clouds:
a group of clouds that have an approximate height between 2.5 and 4.5 Km. These include altostratus and altocumulus clouds.   Cloud Types at Low, Mid and High Levels
M
miles per hour:
a ratio that describes a rate of motion or the ratio of distance traveled (in miles) to the time (in hours) required to travel that distance.  
M
mode:
The most common number in a set of data.  
M
myth:
a set of stories that strives to explain the world and its view of people. This can also be described as a set of stories that is passed down from one generation to another that helps to explain certain themes in a culture.  
M
myths:
plural form of myth. See myth.  
N
navigation:
the process of being able to control, through various methods, a particular craft from one point to another.  
N
nimbostratus:
Low-level clouds that cover the entire sky with broad sheets, and that produce steady rain of low to moderate intensity with no thunder and lightning..   Photo of Nimbostratus Clouds
Image courtesy Photo taken in September 2001 by Robert Sepulveda at Menchville High School, Newport News, VA.
N
nimbus:
type of low-level cloud that usually brings steady precipitation.   NOAA Jetstream website
N
NPOESS Preparatory Project (NPP):
National Polar-orbiting Operational Environmental Satellite System (NPOESS) is the next generation of low Earth orbiting environmental satellites that will be used to study the Earth System. A new Clouds and the Earth's Radiant Energy System (CERES) instrument will be one of the instruments on board the first satellite in the new system, the NPOESS Preparatory Project (NPP). The new CERES instrument and the other four other Earth-observing instruments will monitor atmospheric and sea surface temperatures, humidity, land and ocean biological productivity, cloud and aerosol properties, total/profile ozone measurements, and changes in the Earth's radiation budget. The NPP spacecraft is scheduled for launch into a polar orbit October 25, 2011 from Vandenberg Air Force Base in California on a Boeing Delta II-7920-10 launch vehicle..   NPP Satellite with Earth Image
O
occluded front:
A front in which a warmer or colder air mass, in relation to the air mass (warm front) ahead of it, overtakes the warm front and lifts the warmer air, cutting it off from the Earth's surface. Occluded fronts are usually found around strong low-pressure areas, and are accompanied by a mix of weather.   tutorial on occluded fronts
O
opaque:
refers to materials that allow no light to pass through.   (Also see [link to cloud definition])
O
Opaque Cloud Opacity:
This describes thick clouds which do not allow light to pass directly, although light can diffuse through them. Such thick clouds often look gray. When the sky is overcast, or when these clouds are in front of the Sun, it is impossible to tell where the Sun is..   Opaque Cloud Opacity
O
Optical Depth:
The optical depth is a measure of the visual or optical thickness of a cloud; that is, of the reduction of light or energy transmitted through the cloud due to interactions with the cloud particles. Optical depth is much more significant to Earth's energy budget than the physical thickness of cloud layers. Unlike height, it is not measured in meters or feet; but is nondimensional. An optical depth below 3 is considered to be thin. Anything above 10 is definitely thick. The same term is also used to describe the optical depth of aerosol (dust, smoke, etc) layers..   Optical Depth Graph
O
oxygen:
element number eight on the periodic table of elements. It can be described as a colorless odorless gas that makes up 21 percent of the atmosphere by volume.  
P
Passive Remote Sensing:
This is the traditional way to do remote sensing. A sensor simply collects whatever energy reaches it..  
P
perpendicular:
a straight line that is 90 degrees to another straight line.   Image of Perpendicular line
P
Persistent Non-Spreading Contrails:
A thin contrail that remains in the sky after the plane has disappeared. These contrails are not much wider than the short-lived contrails and are thinner than 1 finger held at arm's length..  
P
Persistent Spreading Contrails:
A thick contrail that remains in the sky after the plane has disappeared. They are wider than 1 finger held at arma's length. These contrails can grow to resemble natural cirrus clouds..   Persistent Spreading Contrail
P
perspective:
This is the relative position that one has in a particular situation.  
P
Polar Orbits:
Polar-orbiting satellites provide a more global view of Earth, circling at near-polar inclination (the angle between the equatorial plane and the satellite orbital plane -- a true polar orbit has an inclination of 90 degrees). Orbiting at an altitude of 700 to 800 km, these satellites cover best the parts of the world most difficult to cover in situ (on site). For example, McMurdo, Antartica, can be seen on 11-12 of the 14 daily NOAA polar-orbiter passes. These satellites operate in a sun-synchronous orbit. The satellite passes the equator and each latitude at the same local solar time each day, meaning the satellite passes overhead at essentially the same solar time throughout all seasons of the year. This feature enables regular data collection at consistent times as well as long-term comparisons. The orbital plane of a sun-synchronous orbit must also rotate approximately one degree per day to keep pace with the Earth's surface..   For more information on orbits.
P
pollution:
The contamination of an environment by human-waste, rendering it undesirable.  
P
precipitation:
Water that falls from clouds to the ground. This can be in the form of rain, snow, sleet, hail, etc.   More info from the Global Precipitation Measurement mission Picture of thunderstorm with heavy rain
P
prediction:
a statement about the occurrence of future events.  
P
proverb:
a short memorable and profound statement that is widely believed to be true.  
Q
query:
(1)the act of posing a question. (2) the act or retrieving information from a search engine.  
R
radiation budget:
The Earth's radiation budget describes the balance of sunlight entering the Earth system, and reflected sunlight and emitted heat leaving the Earth. This is the focus of CERES measurements.   See also Energy Budget Earth Radiation Budget Illustration
R
Radiosonde:
A balloon-borne instrument that measures meteorological parameters from the Earth's surface up to 20 miles in the atmosphere. The radiosonde measures temperature, pressure, and humidity, and transmits or "radios" these data back to Earth. Upper air winds also are determined through tracking of the balloon ascent. Radiosonde observations generally are taken twice a day (0000 and 1200 UTC) around the globe. NOAA's National Weather Service (NWS) operates a network of about 90 radiosonde observing sites in the U.S. and its territories. When the balloons burst, radiosondes return to Earth on a parachute. Approximately 25 percent are recovered and returned to NWS for reconditioning and reuse..  
R
rain:
moisture falling in the form of a droplet resulting from vapor that has been condensed in the atmosphere.   Rain Storm
Image courtesy NASA/Sean Smith
R
rainfall:
the amount of water in rain that fell over a certain area on Earth during a certain amount of time.  
R
rain gauge:
an instrument to record the amount of rainfall in a given area over a set period of time.   Rain Gauge
R
range:
The difference between the highest and lowest numbers in a set of data.  
R
record:
(1)anything that has the ability to show proof of a past event. (2) having the highest or lowest point in a particular data set (i.e yesterdays temperature set the record for the highest temperature in the states history.).  
R
recycle:
To produce a new item using an old item. To reprocess inorganic materials.  
R
reduce:
To use less of a resource.  
R
reflection:
the return of sound or light back to its source. In the atmosphere, the process where incoming solar rays are redirected back upwardly after striking particles. Cloud water and ice account for most reflection of solar radiation.   Diagram of reflection and refraction
Image courtesy University of Virginia
R
relative humidity:
the ratio between the amount of water vapor in the air and the amount required for saturation; depends on atmospheric temperature and pressure.  
R
remote sensing:
Obtaining information about a subject, as with a camera, without being in contact with it. This term is now commonly used in conjunction with electromagnetic techniques for acquiring information. That is, techniques which image part of the electromagnetic spectrum (i.e., visible light, infrared energy (heat), X-rays, ultraviolet light, etc...).  
R
report:
share the findings of an experiment or other research.  
R
reuse:
To use an item more than once.  
R
rotate:
to turn about a central axis.  
R
rotation:
the act of turning about a central axis.  
R
row:
a side-by-side arrangement of objects in a long continual line or strip.  
S
satellite:
Something that is in orbit around something else. For example, the Moon is a natural satellite in orbit around the Earth. Terra and Aqua are artificial satellites put into Earth orbit. The Mars Reconnaissance Orbiter is an artificial satellite put into orbit around Mars. Satellites assist in weather forecasting.   Satellite Tracking site Diagram of TRMM satellite in Earth orbit
Image courtesy NASA
S
Satellite azimuth from North (sat azm fr. north):
The satellite azimuth angle from north. If: point A = the ground site (where you are); point N = the North Pole; point S = the point on the Earth directly under the satellite; then the satellite azimuth angle = angle NAS. Here's another way of thinking of this: Say the angle = 50 degrees. If you stand facing the North Pole and then turn clockwise by 50 degrees, then you will be looking in the direction of the satellite..  
S
saturation:
the atmospheric condition when water will begin to change phase from vapor to liquid or solid; occurs when relative humidity reaches 100 percent, usually by cooling.  
S
scale:
a system of measurement that uses marks shown at regular intervals. The marks represent numerical values.  
S
shadow:
the relative darkness on a surface that occurs when direct sunlight is blocked..   Spirit Shadow over Laguna Trench
Image courtesy NASA Spirit's front hazard-avoidance camera Feb. 21, 2004
S
Sky Color:
The classification of the color of the sky into one of the following 5 categories: Deep Blue, Blue, Light Blue, Pale Blue, and Milky. Near the horizon it is typically lighter due to the presence of aerosols. The darkest part of sky can often be seen about half way between the horizon and directly overhead, in the "anti- sun" direction - that is, when you look at the sky with your shadow in front of you. When observing Sky Color your should classify the darkest (bluest) color of the sky. S'COOL Sky Color Chart.  
S
Sky Visibility:
Viability is the the clarity with which objects can be viewed through the intervening atmosphere. Visibility classifications are Unusually Clear, Clear, Somewhat Hazy, Very Hazy, Extremely Hazy. To judge visibility or atmospheric clarity it is best to look at a distant object like hills of buildings. By repeatedly looking at these distant objects on different days you can gain a sense of the difference between clear days or hazy days..  
S
sleet:
frozen rain.  
S
slide show:
a style of showing pictures in a presentation in which one photograph is viewed right after the other.  
S
snow:
precipitation in the form of ice crystals.   Trees covered with snow
S
Solar Zenith:
The angle between the local zenith and the line of sight to the sun. If: point A = the ground site (where you are); point Z = any point directly above point A (The zenith); point B = the sun; then the solar zenith angle = the angle ZAB..   zentih gif
S
spark:
a quick bright discharge of electricity between two conductors.  
S
spreadsheet:
a computer application that allows the user to manipulate numerical data in user defined ways that can produce user defined outputs.  
S
static:
related to forces, weight, or pressures that act without causing movement.  
S
stationary front:
A boundary between a cold front and a warm front, in which neither is strong enough to overtake the other. There is little or no movement of the two air masses. Stationary fronts are usually accompanied by long periods of rain.   tutorial on stationary fronts
S
station model:
a symbolic way of representing weather station data. It provides a large amount of data that is displayed in a small space, so that multiple stations data can be compared in the same map.  
S
stratocumulus:
These low clouds are a mixture of layered (stratus) and puffy (cumulus) portions. Sometimes they consist of small cumulus bands lined up in neat rows..   S'COOL Cloud Chart - Stratocumulus Clouds Photo by the class of Margaret Holtschlag
S
stratus:
low, gray clouds that may have very little variation. Layered, featureless clouds.   S\'COOL Cloud Chart - Stratus Clouds Stratus Clouds
Image courtesy Pequot Lakes Elementary School, Pequot Lakes, MN
S
sustainable:
To utilize resources in a way to maintain and meet present needs without depleting the resource or compromising future needs.  
T
temperature:
a relative degree of heat, usually measured on a scale such as the Fahrenheit or Celsius scale. Temperature Conversion Tool.  
T
thematic map:
A chart or map that relates a specific theme to a geographical area.  
T
theorize:
to take a guess at causes or reasons.  
T
thermometer:
an instrument for measuring temperature.   thermometer
T
thunder:
the loud noise, usually heard when a thunderstorm is hearby, that is a result of electricity (lightning) disturbing the air.  
T
thunderstorm:
a storm in which a large amount of thunder and lightning is present.   Lightning strikes the launchpad of Space Shuttle Challenger during thunderstorm
Image courtesy Sam Walton
T
tornado:
a rotating column of air usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud.   NOAA Tornado Guide
T
tornado warning:
a tornado warning is an alert issued by government weather services to warn an area that a tornado may be imminent. It can be issued after either a tornado or funnel cloud has already been spotted, or if radar indicates that a tornado may be possible..   NOAA - Storm Predicition Center
T
tornado watch:
a tornado watch is issued when weather conditions are favorable for the development of sever thunderstorms that are capable of producing a tornado..   NOAA - Storm Prediction Center
T
translucent:
refers to materials that allow some light to pass through.   (Also see [link to cloud definition])
T
Translucent Cloud Opacity:
This describes medium-thickness clouds. You can see some sunlight transmitted through them, but not sky. In the photo at right, note that the position of the Sun is quite obvious, even though there is a cloud in front ot it. The amount of light coming through is not all that bright but is enough to note the Sun's position..   Translucent Cloud Opacity
T
transparent:
refers to materials that allow almost all light to pass through.   (Also see [link to cloud definition])
T
Transparent Cloud Opacity:
This describes thin clouds through which light passes easily, and through which you can even see blue sky. Note the milky bluish-whitish appearance of the cirrus clouds at left, especially those near the top of the photo..   Transparent Cloud Opacity
U
Universal Time:
Standard time at longitude = 0 (the longitude line which goes through Greenwich, England) which is used as a standard around the world to assist in synchronizing data collection..   Look here to figure out the time offset from UT to your time zone.
V
validate:
the act of checking a particular set of data to make sure that it is true. This is normally done through comparison to a set of known values.  
V
validation:
the act of verifying the value of data, usually by comparing the data with other data sources. For satellite data, often ground or aircraft based measurements at a particular time and location will be compared to determine how well the data correlates.  
V
Viewing Zenith:
The angle between the local zenith and the line of sight to the satellite. If: point A = the ground site (where you are); point Z = any point directly above point A (The zenith); point C = the satellite, then the viewing zenith angle = the angle ZAC..   zentih gif
V
visual opacity:
relative capacity of a material to allow light to pass through.   (Also see [link to cloud definition])
V
vortex:
a whirling or spinning mass of air or water.  
W
warm front:
The boundary between a warm air mass and a cold air mass, in which the less dense, warm, air mass moves over the colder, more dense, air mass. A warm front is usually followed by warmer, clear weather.   tutorial on warm fronts
W
warning:
a message sent out by meteorologists when weather conditions indicate that a severe storm, such as a blizzard, hurricane, or tornado, has been sighted or indicated by radar.  
W
watch:
a message sent out by meteorologists when weather conditions are possible for formation of a severe storm, such as a blizzard, hurricane, or tornado.  
W
water cycle:
the cycle of water between the ground, the oceans, and the atmosphere (the Earth System)

This cycle is made up of a few main parts:
  • evaporation
  • condensation
  • precipitation
  • collection
.   The Water Cycle for Kids and Students : Beginner, Intermediate and Advanced
Water Cycle
Image courtesy Kid Zone - Fun Facts For Kids
W
water vapor:
water in the form of a gas.  
W
weather:
The state of the atmosphere at a particular place and time. Weather includes variables such as temperature, atmospheric pressure, wind, cloudiness, precipitation, and relative humidity..  
W
weather instruments:
any tool or device that is used to determine various weather conditions.  
W
weather symbols:
small graphic representations of a particular type of weather condition. These are often used on a station model so that whoever is reading the model has access to a large amount of information without the need to read any words.   Weather Symbols
W
wind:
movement of air from one place to another.  
W
wind vane:
a mechanical device that allows the user to easily see the direction of the wind. This device is usually mounted on an elevated structure that does not have anything blocking the wind from the vane.   designing a wind vane image of wind vane

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