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The Earth's atmosphere is divided up into 5 major layers:

Exosphere - The last layer and the thinnest. It goes all the way to 10,000 km above the Earth's surface.

Thermosphere - The thermosphere is next and the air is very thin here. Temperatures can get extremely hot in the thermosphere.

Mesosphere - The mesosphere covers the next 50 miles beyond the stratosphere. This is where most meteors burn up upon entry. The coldest place on Earth is at the top of the mesosphere.

Stratosphere - The stratosphere extends for the next 32 miles after the troposphere. Unlike the troposphere the stratosphere gets its heat by the Ozone Layer absorbing radiation from the sun. As a result, it gets warmer the further away you get from the Earth. Weather balloons go as high as the stratosphere.

Troposphere - The troposphere is the layer next to the ground or surface of the Earth. It covers around 30,000-50,000 feet high. This is where we live and even where planes fly. Around 80% of the mass of the atmosphere is in the troposphere. The troposphere is heated by the surface of the Earth.

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Kids learn about the science of the Earth's Atmosphere. Carbon dioxide, Oxygen, Nitrogen and more make up clouds and weather.

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Clouds

What are clouds?
A cloud is a large collection of very tiny droplets of water or ice crystals. The droplets are so small and light that they can float in the air.
How are clouds formed?

All air contains water, but near the ground it is usually in the form of an invisible gas called water vapor. When warm air rises, it expands and cools. Cool air can't hold as much water vapor as warm air, so some of the vapor condenses onto tiny pieces of dust that are floating in the air and forms a tiny droplet around each dust particle. When billions of these droplets come together they become a visible cloud.

Why are clouds white?
Since light travels as waves of different lengths, each color has its very own unique wavelength. Clouds are white because their water droplets or ice crystals are large enough to scatter the light of the seven wavelengths (red, orange, yellow, green, blue, indigo, and violet), which combine to produce white light.

Why do clouds turn gray?
Clouds are made up of tiny water droplets or ice crystals, usually a mixture of both. The water and ice scatter all light, making clouds appear white. If the clouds get thick enough or high enough all the light above does not make it through, hence the gray or dark look. Also, if there are lots of other clouds around, their shadow can add to the gray or multicolored gray appearance.

Why do clouds float? A cloud is made up of liquid water droplets. A cloud forms when air is heated by the sun. As it rises, it slowly cools it reaches the saturation point and water condenses, forming a cloud. As long as the cloud and the air that its made of is warmer than the outside air around it, it floats!

Clouds move with the wind. High cirrus clouds are pushed along by the jet stream, sometimes traveling at more than 100 miles-per-hour. When clouds are part of a thunderstorm they usually travel at 30 to 40 mph. How do clouds move?

Why do clouds form at different heights in the atmosphere?
The characteristics of clouds are dictated by the elements available, including the amount of water vapor, the temperatures at that height, the wind, and the interplay of other air masses.
There are many different types of fog, but fog is mostly formed when southerly winds bring warm, moist air into a region, possibly ending a cold outbreak. As the warm, moist air flows over much colder soil or snow, dense fog often forms. Warm, moist air is cooled from below as it flows over a colder surface. If the air is near saturation, moisture will condense out of the cooled air and form fog. With light winds, the fog near the ground can become thick and reduce visibilities to zero. How is fog formed?
(Graphic Credit: USA TODAY.)

You need warm air! Southerly winds bring warm, moist air over cold ground or snow.

Fog Forms! Moisture condenses into fog as air is cooled from below.

Cloud Chart

Cloud Group

Cloud Height

Cloud Types

High Clouds = Cirrus

Above 18,000 feet

Cirrus
Cirrostratus
Cirrocumulus

Middle Clouds = Alto

6,500 feet to 18,000 feet

Altostratus
Altocumulus

Low Clouds = Stratus

Up to 6,500 feet

Stratus
Stratocumulus
Nimbostratus

Clouds with Vertical Growth

Cumulus
Cumulonimbus

Special Clouds

Mammatus
Lenticular
Fog
Contrails

Cirrus Clouds
Cirrus clouds are the most common of the high clouds. They are composed of ice and are thin, wispy clouds blown in high winds into long streamers. Cirrus clouds are usually white and predict fair to pleasant weather. By watching the movement of cirrus clouds you can tell from which direction weather is approaching. When you see cirrus clouds, it usually indicates that a change in the weather will occur within 24 hours.

Cirrocumulus clouds appear as small, rounded white puffs that appear in long rows. The small ripples in the cirrocumulus clouds sometime resemble the scales of a fish. Cirrocumulus clouds are usually seen in the winter and indicate fair, but cold weather. In tropical regions, they may indicate an approaching hurricane.

"Alto" Clouds
Stratus clouds are uniform grayish clouds that often cover the entire sky. They resemble fog that doesn't reach the ground. Light mist or drizzle sometimes falls out of these clouds.

Cumulus clouds are white, puffy clouds that look like pieces of floating cotton. Cumulus clouds are often called "fair-weather clouds". The base of each cloud is flat and the top of each cloud has rounded towers. When the top of the cumulus clouds resemble the head of a cauliflower, it is called cumulus congestus or towering cumulus. These clouds grow upward and they can develop into giant cumulonimbus clouds, which are thunderstorm clouds.

Cumulonimbus clouds are thunderstorm clouds. High winds can flatten the top of the cloud into an anvil-like shape. Cumulonimbus clouds are associated with heavy rain, snow, hail, lightning and even tornadoes. The anvil usually points in the direction the storm is moving.
Cumulus Clouds Stratus Clouds
Mammatus clouds are low hanging bulges that droop from cumulonimbus clouds. Mammatus clouds are usually associated with severe weather. Altostratus clouds are gray or blue-gray mid level clouds composed of ice crystals and water droplets. The clouds usually cover the entire sky. In the thinner areas of the clouds, the sun may be dimly visible as a round disk. Altostratus clouds often form ahead of storms with continuous rain or snow.

Lenticular clouds are caused by a wave wind pattern created by the mountains. They look like discs or flying saucers that form near mountains.

Fog is a cloud on the ground. It is composed of billions of tiny water droplets floating in the air. Fog exists if the atmospheric visibility near the Earth's surface is reduced to 1 kilometer or less.

Contrails are condensation trails left behind jet aircrafts. Contrails form when hot humid air from jet exhaust mixes with environmental air of low vapor pressure and low temperature. The mixing is a result of turbulence generated by the engine exhaust. Special Clouds

Fractus clouds are small, ragged cloud fragments that are usually found under an ambient cloud base. They form or have broken off from a larger cloud, and are generally sheared by strong winds, giving them a jagged, shredded appearance. Fractus have irregular patterns, appearing much like torn pieces of cotton candy. They change constantly, often forming and dissipating rapidly. They do not have clearly defined bases. Sometimes they are persistent and form very near the surface.

Green Clouds are often associated with severe weather. The green color is not completely understood, but it is thought to have something to do with having a high amount of liquid water drops and hail inside the clouds. In the Great Plains region of the U.S. green clouds are associated with storms likely to produce hail and tornadoes.

Cloud Activities Lesson Plan: Here is a great lesson plan on clouds. In this activity, kids see clouds form when they breath on spoons. When warm, moist breath hits the cool spoon, water vapor condenses and turns into a cloud--or water you can see. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.
Lesson Plan: Here is a great lesson plan on identifying clouds. In this activity, kids build a cloud finder and identify what clouds they see outside. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.
Lesson Plan: Here is a great lesson plan focusing on different types of clouds, how they are formed, and what they indicate about the weather. This activity is for grades 3-6. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.
Cloud Experiment: Here is a great experiment that allows the kids to make a cloud in a bottle.

Fog Experiment: Here is a great experiment that allows the kids to make fog.
Pressure Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!
Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.
Make A Barometer Experiment: Here is an experiment that allows the kids to make a barometer.

Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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Stuck with your homework? This is the place to be

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Due to Adobe's decision to stop supporting and updating Flash ® in 2020, browsers such as Chrome, Safari, Edge, Internet Explorer and Firefox will discontinue support for Flash-based content. As a result, this site has been retired.

If you have additional questions please contact Savvas Learning Company to find either your sales rep or the technical support form.

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Due to Adobe's decision to stop supporting and updating Flash ® in 2020, browsers such as Chrome, Safari, Edge, Internet Explorer and Firefox will discontinue support for Flash-based content. As a result, this site has been retired. If you have additional questions please contact Savvas Learning Company to find either your sales rep or the technical support form.

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An air mass is a large body of air that has similar moisture (density) and temperature characteristics. A front is a transition zone between two air masses.

A cold front is a warm-cold air boundary with the colder air replacing the warmer. As a cold front moves into an area, the heavier cool air pushes under the lighter warm air that it is replacing. The warm air becomes cooler as it rises. If the rising air is humid enough, the water vapor it contains will condense into clouds and precipitation may fall.

As the cold front moves, warm, moist unstable air is usually replaced by cold, dry stable air.

A warm front is the boundary between warm and cool (or cold) air when the warm air is replacing the cold air. Warm air at the surface pushes above the cool air mass, making clouds and storms. Warm fronts often bring stormy weather. Warm fronts often form on the east side of low-pressure systems where warmer air from the south is pushed north.

A warm front typically replaces cool dry air with warm moist air.

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An air mass is a large body of air that has similar moisture (density) and temperature characteristics. A front is a transition zone between two air masses. A cold front is a warm-cold air boundary with the colder air replacing the warmer.

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Interested in extreme weather events? Then a hurricane-a swirling mass of wind, rain, thunder, and chaos-will intrigue you. Hurricanes begin over tropical and subtropical ocean water. They start when warm water, moist air, and strong winds collide and create a rotating bundle of thunderstorms and clouds. A hurricane might last a few hours or several days.

How Hurricanes Form

Some hurricanes roar onto land bringing punishing wind, torrential rain, walls of water, even tornados. The wind, rain, and water surge wreak havoc on the coastline and damage hundreds of miles inland.

Violent winds flip cars, sink boats, and rip houses apart. Hurricane winds range from 74 miles an hour to 150 ​miles an hour​ or more. Wind creates high waves and pushes the water onto shore. The water surge can be 30 feet high. That's as high as a 3-story building. Storm surges cause most of the fatalities and damage.

In addition to the storm surge, hurricanes bring rain. Lots of rain. In 2009, a storm hammered Taiwan with 114 inches of rain in only three days. Hurricane rains cause landslides, flash floods, and long-term floods.

Because meteorologists can predict and track hurricanes, people living in a hurricane's path can stay safe by advance preparation, including an evacuation plan, creating an emergency kit with food, water, and other supplies (don't forget your pets), and most importantly by listening to local authorities on the best ways to stay safe.

Eye: The eye can be 20-40 miles wide. In the eye, rather than dark clouds and rain, one might see blue sky or a starry night. It's known as the calm center of the storm.

Eyewall: The clouds that swirl around the eyehave the most intense rain and winds, sometimes as fast as 200 miles an hour.

Rain bands: The rain and wind come in heavy bursts in this region and spiral in toward the eyewall. Rain bands are the outside areas of a storm and can be found as far as a few hundred miles from the eye.

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Interested in extreme weather events? Then a hurricane-a swirling mass of wind, rain, thunder, and chaos-will intrigue you. Hurricanes begin over tropical and subtropical ocean water. They start when warm water, moist air, and strong winds collide and create a rotating bundle of thunderstorms and clouds.

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Types of winds include global and local winds

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What are global winds and local winds? What are some examples? Find out more

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Weather Instruments

A THERMOMETER measures the air temperature. Most thermometers are closed glass tubes containing liquids such as alcohol or mercury. When air around the tube heats the liquid, the liquid expands and moves up the tube. A scale then shows what the actual temperature is.

A BAROMETER measures air pressure. It tells you whether or not the pressure is rising or falling. A rising barometer means sunny and dry conditions, while a falling barometer means stormy and wet conditions. An Italian scientist named Torricelli built the first barometer in 1643.

A SLING PSYCHROMETER measures relative humidity, using the cooling effect of evaporation. Two thermometers are used in a sling psychrometer. Wet the cloth of one of the thermometers and swing the psychrometer around a few times. Water evaporates from the cloth, causing the temperatures on that thermometer to be lower the the other.

A RAIN GAUGE measures the amount of rain that has fallen over a specific time period.

A WIND VANE is an instrument that determines the direction from which the wind is blowing.

An ANEMOMETER measures wind speed. The cups catch the wind, turning a dial attached to the instrument. The dial shows the wind speed.

WEATHER MAPS indicate atmospheric conditions above a large portion of the Earth's surface. Meteorologists use weather maps to forecast the weather.
A HYGROMETER measures the water vapor content of air or the humidity.

A WEATHER BALLOON measures weather conditions higher up in the atmosphere.

A COMPASS is a navigational instrument for finding directions.

WEATHER SATELLITES are used to photograph and track large-scale air movements. Then meteorologists compile and analyze the data with the help of computers. YOUR EYES are one of the the best ways to help detect the weather. Always keep an eye at the sky and you'll usually be on top of weather conditions.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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Weather Forecasting

How do meteorologists forecast the weather?
Weather forecasting is a prediction of what the weather will be like in an hour, tomorrow, or next week. Weather forecasting involves a combination of computer models, observations, and a knowledge of trends and patterns. By using these methods, reasonable accurate forecasts can be made up to seven days in advance.

What are weather station symbols?
Weather symbols are used on my weather maps as shorthand for the conditions at weather observing stations.
Click Here to see a complete list of all the weather station symbols.
Click Here for an easy print out of the different weather station symbols.

What is a High Pressure System?
A high pressure system is a whirling mass of cool, dry air that generally brings fair weather and light winds. When viewed from above, winds spiral out of a high-pressure center in a clockwise rotation in the Northern Hemisphere. These bring sunny skies. A high pressure system is represented as a big, blue H.

What is a Low Pressure System?
A low pressure system is a whirling mass of warm, moist air that generally brings stormy weather with strong winds. When viewed from above, winds spiral into a low-pressure center in a counterclockwise rotation in the Northern Hemisphere. A low pressure system is represented as a big, red L.
H
What is a dew point?

What is an air mass?
An air mass is an extremely large body of air whose properties of temperature and moisture content (humidity), at any given altitude, are fairly similar in any horizontal direction. Air masses can cover large (hundreds of miles) areas. Air masses can control the weather for a relatively long time period: from a period of days, to months. Most weather occurs along the periphery of these air masses at boundaries called fronts. There are 4 general air mass classifications categorized according to the source region: polar, tropical, continental and marine.
The dew point is the temperature at which water starts to condense out of a particular air mass. The dew point temperature changes only when the moisture content of the air changes. The higher the dew point, the greater the moisture content is in the air.
What is humidity?
What type of air masses affect the United States?
Humidity is the amount of water vapor in the air.

What is relative humidity?
Relative humidity is the ratio of water vapor contained in the air compared to the maximum amount of moisture that the air can hold at that specific temperature and pressure. Humans are very sensitive to humidity, as the skin relies on the air to get rid of moisture. The process of sweating is your body's attempt to keep cool and maintain its current temperature. If the air is at 100-percent relative humidity, sweat will not evaporate into the air. As a result, we feel much hotter than the actual temperature when the relative humidity is high. If the relative humidity is low, we can feel much cooler than the actual temperature because our sweat evaporates easily, cooling us off. What is a front?
A front is a boundary between two different air masses, resulting in stormy weather. A front usually is a line of separation between warm and cold air masses.

How do you identify a front on a surface weather map or by your own weather observations?
L
What is a cold front?
A cold front is a boundary between two air masses, one cold and the other warm, moving so that the colder air replaces the warmer air. A cold front is represented as a blue line with the teeth pointing toward the direction on movement.

What is a warm front?
A warm front is a boundary between two air masses, one cool and the other warm, moving so that the warmer air replaces the cooler air. A warm front is represented as a red line with half circles pointing toward the direction on movement.

What is a occluded front? What is a trough?
An occluded front is a combination of two fronts that form when a cold front catches up and overtakes a warm front. An occluded front is represented as a purple line with teeth and half circles. What is a stationary front?
A stationary front is a boundary between two air masses that more or less doesn't move, but some stationary fronts can wobble back and forth for several hundred miles a day. A stationary front is represented as an alternating warm and cold front symbol.

1.) Polar latitudes (P) - located poleward of 60 degrees north and south

2.) Tropical latitudes (T) - located within about 25 degrees of the equator

3.) Continental (c) - located over large land masses, dry

4.) Marine (m) - located over the oceans

What is a weather satellite?
A weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be either polar orbiting, seeing the same swath of the Earth every 12 hours, or geostationary, hovering over the same spot on Earth by orbiting over the equator while moving at the speed of the Earth's rotation. These meteorological satellites see more than clouds and cloud systems. City lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, etc., are other types of environmental information collected using weather satellites.
We can then make combinations of the above to describe various types of air masses.
What is radar?

How does Doppler Radar work?

What is NEXRAD Radar?
The National Weather Service has installed a new type of Doppler Radar called NEXRAD Radar. NEXRAD stands for Next Generation Radar. This radar produces many different views of storms and rain that allows meteorologists to determine if a storm could be severe. Can animals predict weather?
If your dog always comes inside right before it rains, you may think that animals can predict the weather. It's probably more accurate to say that animals react to certain environmental signals that accompany weather changes, not to the weather itself. A prevalent opinion is that animals can detect certain events, like earthquakes, as soon as they happen, even if the originating event is a great distance away. The majority of researchers say that animals make greater use of their existing five senses, especially when compared to humans. The most critical sense is hearing.
Doppler Radar gets its name from the Doppler Effect. Have you ever listened to a train whistle as it was coming toward you? You probably noticed that the pitch of the whistle changed as the train passed you and moved away. This change in the frequency of sound is called the Doppler Effect. Doppler Radar measures the changes in the frequency of the signal it receives to determine the wind. Weather Forecasting Activities
Lesson Plan: Here is a great lesson plan on learning how to forecast. In this activity, kids learn about different forecasting tricks. What is Doppler Radar?
Doppler Radar detects precipitation intensity, wind direction and speed, and provides estimates of hail size and rainfall amounts. Doppler Radar gives forecasters the capability of providing early detection of severe thunderstorms that may bring strong damaging winds, large hail, heavy rain, and possibly tornadoes. Combined with satellites, radar gives forecasters the ultimate tools to provide accurate forecasts and advanced severe weather warnings.Lesson Plan: Here is a great lesson plan on weather symbols for younger kids. This lesson plan requires kids to match the weather symbols to words. You will need to download this file to then be able to print off copies for your students.
Radar is an electronic instrument, which determines the direction and distance of objects that reflect radio energy back to the radar site. It stands for Radio Detection and Ranging. This is what meteorologists use to see rain or snow.
The Doppler Effect Experiment: Here is a an experiment that teaches kids what the Doppler Effect is. They can learn how the Doppler Effect works and why Doppler Radar is such an important tool in weather forecasting.

cP continental polar cold, dry, stable

cT continental tropical hot, dry, stable air aloft, unstable surface air

mP maritime polar cool, moist, and unstable

mT maritime tropical warm, moist, usually unstable

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.
There are many types of air masses that can affect the U.S., since it is such a large country. Below are a few examples:

cP - wintertime bitter cold can extent to Southern U.S. and even Florida causing crop damage. Require long, clear nights, which means strong radiational cooling of air near the surface. A stable air mass. Little moisture added so air is dry

mP - Winter cP air moves over a region such as the NE Pacific, picking up some warmth and moisture from the warmer ocean. In the case of the Pacific NW mountains force the air to rise (orographic lifting) causing rain.

mT - wintertime source for the SW U.S. is the subtropical East Pacific Ocean. mT air that influences weather east of the Rocky Mountains comes from the Gulf of Mexico, but only influences winter weather in the SE states. Occasionally, slow moving weather systems in SW flow aloft can draw up moisture at mid and low levels producing precipitation.

cT - Continental tropical air usually only influences the U.S. in summertime as warm, dry air is pumped up off of the Mexican Plateau. It is usually fairly stable and dry, and if it becomes stagnant over the Midwest, results in a drought. Deaths associated with the 1995 heat wave in the Midwest were the result of cT and mT air which stagnated over the central and eastern part of the U.S.

Look for: Sharp temperature changes over a relatively short distance, change in moisture content, rapid shifts in wind direction, pressure changes, clouds and precipitation patterns.

A trough on a weather map is an elongated area of relatively low pressure. Troughs bring cloudy and rainy weather. A trough is represented by a hash mark line.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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A greenhouse is a house made of glass. It has glass walls and a glass roof. People grow tomatoes and flowers and other plants in them. A greenhouse stays warm inside, even during winter. Sunlight shines in and warms the plants and air inside. But the heat is trapped by the glass and can't escape.