Cloud Formations Sunlight causes water to evaporate into the atmosphere. The air now contains the water vapor and is heated at the surface of the Earth.

Cloud FormationsCloud Formations

Sunlight causes water to evaporate into the atmosphere. The air now contains the water vapor and is heated at the surface of the Earth and rises. As the air rises, it cools and the water

vapor condenses forming clouds.

Condensation on spider webs. Views of early morning fog in IndianaCondensation on spider webs. Views of early morning fog in Indiana

CONDENSATIONCONDENSATION

Importance of CloudsImportance of Clouds

• So, what is a cloud?So, what is a cloud?

~ It is a thick mass of water vapor or ice ~ It is a thick mass of water vapor or ice crystals that LOVE to stick together.crystals that LOVE to stick together.

• What do clouds tell us?What do clouds tell us?

~ ~ Meteorlogists use the presence of Meteorlogists use the presence of clouds to signal that there will be changes in clouds to signal that there will be changes in the weather. the weather. Predicting the weather requires Predicting the weather requires the understanding of the different types of the understanding of the different types of cloudsclouds

Identifying CloudsIdentifying Clouds

To better communicate and understand the many cloud To better communicate and understand the many cloud forms in the sky, meteorologists identify clouds based forms in the sky, meteorologists identify clouds based

on five basic cloud characteristics: on five basic cloud characteristics:

1. The altitude at which they occur 1. The altitude at which they occur 2. Color2. Color

3. Density 3. Density 4. Shape4. Shape

5. Degree of cover. 5. Degree of cover.

From this information, we can identify three basic cloud From this information, we can identify three basic cloud types and seven other common cloud types.types and seven other common cloud types.

Using these characteristics you can identify the Using these characteristics you can identify the three basic cloud types:three basic cloud types:

Stratus, Stratus, Cirrus, and Cirrus, and

CumulusCumulus

Cloud TypeCloud Type

Stratus CloudsStratus CloudsStratus clouds Stratus clouds are thin, sheet-like clouds. They are are thin, sheet-like clouds. They are layered with some rippling, and cover large portions layered with some rippling, and cover large portions of the sky. They are frequently gray and thick. of the sky. They are frequently gray and thick. Stratus clouds are formed low in the atmosphere Stratus clouds are formed low in the atmosphere when air is forced up when air is forced up slowlyslowly. . Heavy precipitation Heavy precipitation does not usually fall does not usually fall from stratus clouds, but from stratus clouds, but moderate rainfall or snowfall is possiblemoderate rainfall or snowfall is possible

Cirrus CloudsCirrus Clouds

Cirrus clouds are thin, white Cirrus clouds are thin, white clouds with a feathery clouds with a feathery appearance. appearance.

They are the highest of all They are the highest of all clouds forming at heights of clouds forming at heights of 30,000 feet or more above the 30,000 feet or more above the Earth's surface, where the air Earth's surface, where the air is very cold.Cirrus clouds are is very cold.Cirrus clouds are formed by ice crystals. formed by ice crystals.

TheyThey generally occur in fair generally occur in fair weather and point in the weather and point in the direction of air movement at direction of air movement at their elevation. Cirrus clouds their elevation. Cirrus clouds are usually the first sign of an are usually the first sign of an approaching storm. approaching storm.

Sun Pillar

Cirrus Cloud PhenomenonCirrus Cloud Phenomenon

Sometimes, when the sun is just below the horizon, aligned ice crystals reflect light from Sometimes, when the sun is just below the horizon, aligned ice crystals reflect light from their crystal faces. We see the cumulative effect of millions of reflections of this sunlight their crystal faces. We see the cumulative effect of millions of reflections of this sunlight as a sun pillar.as a sun pillar.

Cumulus Clouds:Cumulus Clouds:

Cumulus clouds are flat-based, Cumulus clouds are flat-based, “puffy” clouds with vertical “puffy” clouds with vertical doming. Often grey or white in doming. Often grey or white in appearance, the top of cumulus appearance, the top of cumulus clouds have a "cauliflower-like" clouds have a "cauliflower-like" look.look.

They can cover a great deal of They can cover a great deal of the sky.the sky.

Cumulus clouds form when air Cumulus clouds form when air is forced up rapidly and is forced up rapidly and therefore rises higher. therefore rises higher.

Cumulus clouds are most Cumulus clouds are most prominent during the summer prominent during the summer months. They indicate fair months. They indicate fair weather but as a cumulus cloud weather but as a cumulus cloud grows, rain can develop.grows, rain can develop.

Watch for Stratus and Cirrus CloudsWatch for Stratus and Cirrus Clouds    Steps:Steps: 1.  Think "flat" when you're identifying stratus clouds.  1.  Think "flat" when you're identifying stratus clouds.  

2.  Remember, high altitude cirrostratus clouds appear as thin, wispy 2.  Remember, high altitude cirrostratus clouds appear as thin, wispy sheets.  sheets.  

3.  Look for stratus clouds at any altitude.  3.  Look for stratus clouds at any altitude.  

4.  Look high into the sky for cirrus clouds.  4.  Look high into the sky for cirrus clouds.  

5.  Remember, cirrus clouds consist of moisture thrown up by distant 5.  Remember, cirrus clouds consist of moisture thrown up by distant storms and turned to ice.  storms and turned to ice.  

6.  Watch for thin, hair-like, disconnected wisps of clouds at altitudes 6.  Watch for thin, hair-like, disconnected wisps of clouds at altitudes above 18,000 feet.  above 18,000 feet.  

Watch for Cumulus CloudsWatch for Cumulus Clouds   

Steps:Steps:

1.  Think "puffy" when you want to identify cumulus clouds.  1.  Think "puffy" when you want to identify cumulus clouds.  

2.  Make a comparison to masses of cotton balls or piles of 2.  Make a comparison to masses of cotton balls or piles of whipped cream.  whipped cream.  

3.  Remember, cumulus clouds are the clouds we used to 3.  Remember, cumulus clouds are the clouds we used to look at and imagine they were people, shapes, animals, etc.look at and imagine they were people, shapes, animals, etc.

Fog :Fog : Clouds at ground levelClouds at ground levelRadiation fog:Radiation fog: forms at night when cold ground cools the air above it forms at night when cold ground cools the air above it

(in valleys)(in valleys)Advection fog:Advection fog: forms when warm, moist air moves over colder forms when warm, moist air moves over colder

surface and cools (in coastal areas)surface and cools (in coastal areas)

FogFog

In this fog, off the coast of Oregon, a cold ocean current cools the air to In this fog, off the coast of Oregon, a cold ocean current cools the air to the air’s dew point temperature. This cooling of the air created the fog. the air’s dew point temperature. This cooling of the air created the fog.

This is called:This is called:

Advection FogAdvection Fog

Warm Water

Cold Air

Evaporation

Condensation

For the development of this fog, warm water is evaporating into cool air. For the development of this fog, warm water is evaporating into cool air. The cool air becomes saturated (its relative humidity becomes 100%) and The cool air becomes saturated (its relative humidity becomes 100%) and condensation creates the fog. This is called:condensation creates the fog. This is called:

Radiation FogRadiation Fog

Cloud Type by RainCloud Type by Rain Finally, we can classify them based on the Finally, we can classify them based on the presence of rainpresence of rain

Nimbus:Nimbus: any cloud that rainsany cloud that rains

Cumulonimbus:Cumulonimbus: taller, towering taller, towering versions of cumulus clouds. versions of cumulus clouds. Their height can be from two to Their height can be from two to five miles. These clouds often five miles. These clouds often form thunderstorms.form thunderstorms.

Nimbostratus:Nimbostratus: low, flat clouds that are are often associated with steady often associated with steady precipitation and occur in thick, precipitation and occur in thick, continuous layers and are often dark continuous layers and are often dark gray in color. gray in color.

Cumulonimbus CloudsCumulonimbus Clouds As seen from Apollo 8 As seen from Apollo 8

T H E E N D