CloudsWhat 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?Clouds are white because they reflect the light of the sun. Light is made up of colors of the rainbow and when you add them all together you get white. The sun appears a yellow color because it sends out more yellow light than any other color. Clouds reflect all the colors the exact same amount so they look white.

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!

How do clouds move?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.

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.

How is fog formed?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. (Graphic Credit: USA TODAY.)

Cirrus CloudsCirrus 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.

Cirrostratus clouds are thin, sheetlike high clouds that often cover the entire sky. They are so thin that the sun and moon can be seen through them. Cirrostratus clouds usually come 12-24 hours before a rain or snow storm.

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" CloudsAltostratus 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.

Altocumulus clouds are mid level clouds that are made of water droplets and appear as gray puffy masses. They usually form in groups. If you see altocumulus clouds on a warm, sticky morning, be prepared to see thunderstorms late in the afternoon.

Stratus CloudsStratus 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.

Stratocumulus clouds are low, puffy and gray. Most form in rows with blue sky visible in between them. Rain rarely occurs with stratocumulus clouds, however, they can turn into nimbostratus clouds.

Nimbostratus clouds form a dark gray, wet looking cloudy layer associated with continuously falling rain or snow. They often produce precipitation that is usually light to moderate.

Cumulus CloudsCumulus 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 it 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.

Special CloudsMammatus clouds are low hanging bulges that droop from cumulonimbus clouds. Mammatus clouds are usually associated with severe weather.

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.

Green Clouds are often associated with severe weather. They form when the clouds are illuminated by light reflected off green vegetation, such as large corn

fields or a heavily wooded forest. In the Great Plains region of the U.S. green clouds are associated with storms likely to produce tornadoes.

Cloud Chart Cloud Group Cloud Height Cloud Types

High Clouds = Cirrus Above 18,000 feetCirrus

CirrostratusCirrocumulus

Middle Clouds = Alto 6,500 feet to 18,000 feet AltostratusAltocumulus

Low Clouds = Stratus Up to 6,500 feetStratus

StratocumulusNimbostratus

Clouds with Vertical Growth CumulusCumulonimbus

Special CloudsMammatusLenticular

FogContrails

Information from : http://www.weatherwizkids.com/cloud.htm

Reading Comprehension: Informational/WeatherName: ________________________________ Date: ___________________________©2004abcteach.comCLOUDSClouds are an important part of the water cycle. Thewater cycle is the movement of water from the Earth into thesky and then back down to Earth again. Did you know thatover 70% of the Earth is covered in water? Water on Earth is in the form of saltwater (97%), the water that is found in the oceans and saltwater lakes, and freshwater (3%), the water that is found in rivers, ponds, lakes, streams andunderground. The sun heats water on the surface of the Earth, and causes it toevaporate. Evaporation is the process when water moves from being a liquid tobeing vapor. Water vapor is made up of tiny water droplets in the air. Water canalso move into the air through transpiration. Transpiration is the movement ofwater out of plants. During photosynthesis, plants make oxygen and water. Waterthen moves out of tiny holes on the leaves and into the air. The water vapor risesup into the atmosphere, and as it cools, it condenses. When the water vaporcondenses it forms clouds. Precipitation happens when so much water vaporcondenses that the air cannot hold it anymore. The clouds get so heavy thatsome of the water must fall back down to Earth as rain, snow, sleet or hail.

There are many different types of clouds. The type of cloud depends onhow high up in the atmosphere the water condenses. The atmosphere is theblanket of air that covers the Earth.Stratus cloudsStratus clouds occur below 6,000 feet. These clouds look like flat sheets ofclouds, and can mean an overcast or rainy day. These clouds are usually auniform color of gray, and cover most of the sky.Cumulus cloudsCumulus clouds are also below 6,000 feet, and look like big fluffy balls ofcotton! They usually mean that the weather will be nice; however, sometimesthey can get very tall and turn into thunderheads. These clouds are usually flaton the bottom, but have very lumpy tops. Cumulus clouds usually form alone,and there is a lot of blue sky between different clouds.Cirrus cloudsThese wispy clouds usually form above 18,000 feet. Cirrus cloudsgenerally move from west to east. They form when water vapor forms icecrystals, and they are so thin because of the height at which they form. There isvery little water vapor above 18,000 feet, and so big thick clouds cannot form.These are the three main types of clouds that can form; however, there arealso several combination clouds.Reading Comprehension: Informational/Weather

Name: ________________________________ Date: ___________________________©2004abcteach.comCombination CloudsStratocumulus clouds usually form below 6,000 feet, and usually form inrows or patches, with blue sky in between. The color of stratocumulus clouds canbe from white to dark gray, but precipitation hardly ever falls from these clouds.Nimbostratus clouds also form below 6,000 feet, and usually produce asteady form of precipitation. Steady precipitation isn’t like a hard thunder shower,but can instead last for several hours or even more than a day. Nimbostratusclouds are so thick that you can’t see the sun or the moon through them.Altostratus clouds form higher than stratocumulus or nimbostratus clouds.They form between 6,000 and 20,000 feet. Altostratus clouds cover the entire skyover a large area, and usually produce steady precipitation ahead of a storm.You can see a bit of the sun through the clouds, but the sun will be hazy or‘watery’. Even though you can see the sun, altostratus clouds do not let enoughsunlight through to produce shadows.Altocumulus clouds also form between 6,000 and 20,000 feet. Theseclouds look like puffy gray balls or blobs, and sometimes appear in rows. Part ofthese clouds is usually darker than the rest, and this helps to set them apart from

higher cirrocumulus clouds. If you see these clouds on a hot summer morning itoften means that there will be thunderstorms in the afternoon.Cirrostratus clouds form even higher than most altostratus andaltocumulus clouds, at above 18,000 feet. These clouds are so thin that you cansee the moon and the sun clearly. Sometimes you only know that there arecirrostratus clouds in the sky because you can see a fuzzy halo around the sunor the moon. This halo is caused because the ice crystals in the cloud bend thelight from the sun and the moon. Cirrostratus clouds usually mean that there willbe rain or snow within 24 hours.Other mixed clouds that form high in the sky are cirrocumulus clouds. Theyalso form above 18,000 feet. They can look like small rounded puffs or cottonballs, either alone or in rows. When the puffs are in rows, the sky has a ripplinglook, and this is how you can tell that they are cirrocumulus clouds, and not cirrusor cirrostratus clouds.Finally, there are the cumulonimbus clouds. These clouds arethunderstorm clouds. The word nimbus or nimbo means precipitation producingcloud. Nimbostratus clouds produce steady rain and cumulonimbus cloudsproduce thunderstorms.Clouds can be fluffy and white, or heavy and gray. They can bring rain andsnow, or day long drizzle. But whatever color or shape they come in, they still dothe same thing. They return water to the Earth, and they are an important part ofthe water cycle.Reading Comprehension: Informational/Weather

Name: ________________________________ Date: ___________________________©2004abcteach.comQuestions on Clouds1. How much of the Earth is covered in water?__________________________________________________________________2. How is the water on Earth split up?__________________________________________________________________3. What is evaporation?__________________________________________________________________4. What is the process called when water moves from plants into the air?__________________________________________________________________5. Describe the water cycle. Include how water moves into the air and back to Earth.______________________________________________________________________________________________________________________________________________________________________________________________________6. What is the atmosphere?__________________________________________________________________7. Describe the three main cloud types.

a) ______________________________________________________________________________________________________________________________b) ______________________________________________________________________________________________________________________________c) ______________________________________________________________________________________________________________________________8. What cloud types occur above 18,000 feet? Include mixed types in your answer.____________________________________________________________________________________________________________________________________9. What happens with nimbostratus clouds?____________________________________________________________________________________________________________________________________10. If you see altocumulus clouds on a summer morning, what do you think mighthappen in the afternoon?__________________________________________________________________11. You have been waiting all summer for the first snowfall. It’s almost here! What typeof cloud will tell you that snow may be coming, and from what type of cloud willsnow fall?______________________________________________________________________________________________________________________________________________________________________________________________________12. What do the words nimbo and nimbus mean?__________________________________________________________________Reading Comprehension: Informational/Weather

Name: ________________________________ Date: ___________________________©2004abcteach.comAnswers to Clouds1. 70% of the Earth is covered in water.2. 97% of water is saltwater and 3% is freshwater.3. Evaporation is the process through which water moves from being a liquid tobeing vapor.4. The process by which water moves from plants into air is called transpiration.5. The sun heats the water and causes the water to evaporate. Water also entersthe air through transpiration. Water vapor moves up through the air until itcondenses into clouds. When so much water has condensed that the air cannothold it any longer precipitation occurs. Water falls back to Earth as rain, snow,sleet or hail.

6. The atmosphere is the blanket of air that covers the Earth.7. a) Stratus clouds – occur below 6,000 feet and look like flat sheets of clouds.They are usually gray and cover most of the sky.b) Cumulus clouds – occur below 6,000 feet and look like fluffy balls of cotton.Usually mean nice weather, but can turn into thunderheads. Flat on the bottomand lumpy on top.c) Cirrus clouds – occur above 18,000 feet. Form when water vapor forms icecrystals. They are so thin because there isn’t much water vapor above 18,000feet.8. Cirrus clouds, altostratus clouds, altocumulus clouds, cirrostratus clouds andcirrocumulus clouds can all form over 18,000 feet.9. Nimbostratus clouds form below 6,000 feet and produce a steady form ofprecipitation. They are so thick that you can’t see the sun or the moon.10. Altocumulus clouds on a hot summer morning can mean that a thunderstorm willform in the afternoon.11. Cirrostratus clouds usually mean that there will be rain or snow in 24 hours, andeither nimbostratus or cumulonimbus clouds will bring snow.12. The words nimbo and nimbus mean ‘precipitation producing cloud’.

CLOUD IN A BOTTLE MATERIALS:

2-liter clear plastic pop bottle matches (children will need adult assistance to light matches) warm water

PROCESS:Fill the clear plastic 2-liter bottle one-third full of warm water and place the cap on. As warm water evaporates, it adds water vapor to the air inside the bottle. This is the first ingredient to make a cloud.

Squeeze and release the bottle and observe what happens. You’ll notice that nothing happens. Why? The squeeze represents the warming that occurs in the atmosphere. The release represents the cooling that occurs in the atmosphere. If the inside of the bottle becomes cover with condensation or water droplets, just shake the bottle to get rid of them.

Take the cap off the bottle. Carefully light a match and hold the match near the opening of the bottle.

Then drop the match in the bottle and quickly put on the cap, trapping the smoke inside. Dust, smoke or other particles in the air is the second ingredient to make a cloud.

Once again, slowly squeeze the bottle hard and release. What happens? A cloud appears when you release and disappears when you squeeze. The third ingredient in clouds is a drop in air pressure.

EXPLANATION:Water vapor, water in its invisible gaseous state, can be made to condense into the form of small cloud droplets. By adding particles such as the smoke enhances the process of water condensation and by squeezing the bottle causes the air pressure to drop. This creates a cloud!