- Slides: 22
“Cloud Formation” I. Cloud Formation: A. Cloud- A collection of millions of tiny water drops in the air. B. Why are there clouds in the sky? 1. Clouds start to form when a parcel of warm moist air starts to rise. 2. Parcel- A small contained area of air. 3. As the parcel gets higher it cools and expands. 4. Cold air can’t hold as much H 2 O as warm air. 5. The parcel will reach saturation eventually. 6. If the parcel of air reaches saturation, H 2 O will condense onto any solid object. (Dust, salt, smoke, etc. )
7. If the parcel is allowed to keep on rising millions of H 2 O drops condense onto this stuff. 8. That is when a cloud is formed. II. Why do clouds form in certain areas? A. Air can be stable or unstable. 1. Stable Air- When a rising parcel of air becomes cooler than the air around it. . A. ) High Pressure B. ) If the air becomes stable it will sink. C. ) If that happens before the air is saturated, a cloud will not form.
2. Unstable Air- When a parcel of air is warmer than the air around it. A. ) Low Pressure B. ) If the air stays unstable it will continue to rise. C. ) If it reaches the saturation level it will form a cloud.
III. Cloud Classification: A. There are three main types of clouds. 1. Cirrus: A. ) Thin feather like clouds. B. ) High altitude. C. ) No precipitation. D. ) Can be a clue that a storm is approaching. 2. Cumulus: A. ) Thick puffy clouds. B. ) Some are cauliflower shaped. C. ) Thunderstorms and hail are come in some types.
3. Stratus: A. ) Light gray, thin layered clouds. B. ) Low altitude. C. ) Light precipitation in most types. D. ) Fog is an example. B. Cloud Types: 1. There are five words that can be attached to the main cloud types, to give them a more specific name. A. ) Cirro- High altitude clouds. B. ) Alto- Mid altitude clouds. C. ) Strato- Low altitude clouds. D. ) Nimbo & Nimbus- Very dark heavy rain clouds.
C. Examples: 1. Cumulonimbus: A. ) Cumulus cloud that grew into a very large, dark, heavy rain cloud. B. ) This type of cloud is the heaviest rainmaker. C. ) Thunderstorms, and tornadoes are common. 2. Nimbostratus: A. ) Huge layers of dark. , low altitude, rain clouds. B. ) Very long periods of rain can fall from these clouds.
I. High Clouds: 1. Cirrus 2. Cirrostratus 3. Cirrocumulus II. Middle Clouds: 1. Altostratus 2. Altocumulus III. Low Clouds 1. Stratus 2. Stratocumulus 3. Nimbostratus IV. Clouds with vertical development: 1. Cumulus 2. Cumulonimbus
IV. Precipitation: A. There are 5 types of precipitation. 1. Rain- Drops of H 2 O falling into areas of above freezing temps. . 2. Snow- H 2 O that falls as a frozen six sided, flake. 3. Sleet- Forms when snow falls through a warm area of air, melts, then freezes back into an ice pellet. 4. Hail- Warm weather falling lumps of ice. A. ) Most commonly found in cumulonimbus clouds. . B. ) Water freezes in the upper level of the cloud, into a small ice pellet.
C. ) When it falls it gets caught in the strong up drafts of wind. D. ) The up drafts blow the ice pellet back into the freezing temperatures. E. ) Another layer of ice forms around it. F. ) The process continues until the ice pellets are too heavy for the up drafts. G If the ice pellet does not melt before it hits the ground you will see hail. 5. Freezing rain- Rain drops that are “super cooled”. A. ) Salt dissolved in rain lowers the freezing point of H 2 O. B. ) As soon as it touches a solid surface it freezes to it.
“Weather Patterns” I. What causes our weather to change? : A. The movement of different air masses causes weather to change. 1. Air Mass- Large body of air that has the same characteristics as the same area it formed over. B. There are four basic air massed that effect weather in United States. 1. Continental Polar (c. P)- Form over cold dry areas. A. ) c. P air masses bring clear skies, and cold temperatures. B. ) Come from Canada.
2. Continental Tropical (c. T)- Form over warm dry areas. A. ) c. T air masses bring clear skies and warm temperatures. B. ) Come from Mexico. 3. Maritime Polar (m. P)- Form over cold wet areas. A. ) m. P air masses bring cloudy skies and cold temperatures. B. ) Come from the Northern Pacific, or the Northern Atlantic.
4. Maritime Tropical (m. T)- Form over warm moist areas. A. ) m. T air masses bring cloudy skies and warm temperatures. B. ) Come from the Gulf of Mexico. (Provides the majority of moisture to eastern storms)
Blues =cold/dry Green =cold/moist Pink =hot/moist Red =hot/dry
C. Why do air masses change weather? 1. These four air mass types can be either stable or unstable. 2. When two different air masses collide weather changes may occur. 3. The boundary between the two air masses is called a front.
II. Fronts: A. What are fronts? 1. Front The boundary between two different air masses. 2. If air between the boundaries is unstable then clouds will form and a storm may occur. show me
B. There are four types of fronts: 1. Warm Front- Happens when a warm air mass moves into a cold air mass. A. ) The warm air will rise over the cold air slowly. B. ) If the air is wet, clouds of the stratus and cumulus variety will form.
C. ) If the air is dry it will bring nice weather with some high cirrus clouds. D. ) On a weather map they look like this: Warm Air Cold Air 2. Cold Front- Happens when a cold air mass moves into a warm air mass. A. ) The cold air forces the warm air to rise quickly.
2. Cold Front- Happens when a cold air mass moves into a warm air mass. A. ) The cold air forces the warm air to rise quickly. B. ) Makes the air rise twice as fast as warm fronts.
C. ) This rapid movement can cuse large rain clouds if the air is wet. . D. ) Large cumulus and nimbostratus clouds are common. E. ) On a weather map they look like this: . Cold Air Warm Air
3. Occluded Front- Happen when two cold air masses collide and force a warm air mass between them to rise. A. ) Very heavy rain will occur if the air mass is wet enough.
B. ) Cumulonimbus clouds and high winds are common. C. ) This is the severe weather front. D. ) If air is dry high winds and moderate rain clouds are still common. E. ) On a weather map they look like this:
Happens when pressure differences cause a 4. Stationary Front- warm front and a cold front to stop moving towards each other. A. ) This type of front may stay in the same area for days. B. ) If the air is wet, light precipitation and wind can last for as long as the front is stationary. C. ) Nimbostratus clouds are common. D. ) If the air is dry light winds and stratus clouds are common. E. ) On a weather map they look like this: Warm Air Cold Air