Cloud FormationsCloud Formations

C R TSWATSWAC R TSWATSWA

Heat causes water to evaporate into the atmosphere. This air containing the water vapour is heated at the surface of the earth and rises. As the air rises, it cools and the water vapour condenses on some form of particulate matter such as dust, ash, or smoke to form clouds. The particulate matter are called Condensation Nuclei.

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

Definition.Definition. ~ Clouds are a thick mass of suspended ~ Clouds are a thick mass of suspended

water droplets or ice crystals.water droplets or ice crystals.

~ ~ The presence of clouds in the sky is The presence of clouds in the sky is one type of signal to meteorologists that there one type of signal to meteorologists that there will be changes in the weather. Predicting the will be changes in the weather. Predicting the weather requires the understanding of the weather requires the understanding of the different types of cloudsdifferent types of clouds

Identifying CloudsIdentifying Clouds

Meteorologists identify clouds based on five basic Meteorologists identify clouds based on five basic cloud characteristics: 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.

One form of classification is based on One form of classification is based on appearance or appearance or formform. Using these characteristics you can identify the . Using these characteristics you can identify the three basic cloud types:three basic cloud types: stratus, cirrus, and cumulusstratus, cirrus, and cumulus

Cloud Type by FormCloud Type by Form

Stratus CloudsStratus CloudsStratus clouds are thin, sheet-like clouds. They are Stratus clouds are thin, sheet-like clouds. They are layered with some rippling, and cover large portions of the layered with some rippling, and cover large portions of the sky. They are frequently gray and thick. Stratus clouds sky. They are frequently gray and thick. Stratus clouds are formed when air is forced up are formed when air is forced up slowlyslowly..

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. earth's surface.

Cirrus clouds are formed by Cirrus clouds are formed by ice crystals. 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.

Cumulus Clouds:Cumulus Clouds:

Cumulus clouds are flat-Cumulus clouds are flat-based, billowing clouds with based, billowing clouds with vertical doming. Often the top vertical doming. Often the top of cumulus clouds have a of cumulus clouds have a "cauliflower-like" appearance. "cauliflower-like" appearance. Cumulus clouds are most Cumulus clouds are most prominent during the summer prominent during the summer months.months.

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

Cloud Type by AltitudeCloud Type by Altitude

Clouds can also be classified based on their Clouds can also be classified based on their altitudealtitude

There are three categories of cloud heights:There are three categories of cloud heights:

High Clouds = Cirrus High Clouds = Cirrus

Middle Clouds = Alto Middle Clouds = Alto

Low Clouds = StratusLow Clouds = Stratus

High clouds: 7-18kmHigh clouds: 7-18km

Cold: less than 25Cold: less than 25ooC & made up of ice C & made up of ice crystalscrystals

Cirrostratus:Cirrostratus: high, wispy clouds. They give the sky a milky white appearance.

CirroCirro

CirrocumulusCirrocumulus:: delicate clouds delicate clouds appearing in bands or ripples across appearing in bands or ripples across the sky. They are one of the least the sky. They are one of the least common of the cloud types.common of the cloud types.

Altostratus:Altostratus: thin, layered clouds that thin, layered clouds that are blue-gray or whitish in color and are blue-gray or whitish in color and often cover large portions of the sky. often cover large portions of the sky. They are thinner if formed at higher They are thinner if formed at higher altitudes but are heavier and more dense altitudes but are heavier and more dense if closer to the ground. if closer to the ground.

* Picture of altocumulus clouds taken by satellite* Picture of altocumulus clouds taken by satellite

Altocumulus:Altocumulus: oval or eliptical in shape, and oval or eliptical in shape, and can have gray undersides. They often have a can have gray undersides. They often have a

"cottonball-like" appearance."cottonball-like" appearance.

AltoAltoTheseThese clouds usually form from the gradual lifting of air in advance of a cold clouds usually form from the gradual lifting of air in advance of a cold

front. front.

Middle level clouds: 2-7 kmMiddle level clouds: 2-7 km

0-250-25ooC & composed of both water and ice crystalsC & composed of both water and ice crystals

The presence of altocumulus clouds on a warm and humid summer morning is The presence of altocumulus clouds on a warm and humid summer morning is commonly followed by thunderstorms later in the day.commonly followed by thunderstorms later in the day.

Stratus:Stratus: Dense, uniform dark gray layers.

Stratocumulus:Stratocumulus: groups of dense, puffy clouds that cover the sky in dark heavy masses, long and gray. The often form in bands across the sky.

Low level clouds: 0 - 4 kmLow level clouds: 0 - 4 km

Greater than 5Greater than 5ooC & composed of waterC & composed of water

StratoStrato

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