Objectives: S.W.B.A.T.

Transcription

1 Objectives: S.W.B.A.T. Describe basic cloud formation Define condensation nucleus, fog, Identify 3 basic cloud forms Understand that clouds are based on shape and altitude location in troposphere.

2 Activities: Warm-up Notes/discussion Cloud types 1-4 worksheet

3 20-2 Cloud formation & types

4 Cloud Formation A cloud is a collection of small water droplets or ice crystals suspended in the air -forms when the air is cooled and condensation occurs

5 Cloud Formation For water vapor to condense and form a cloud: A. the air must be saturated with water vapor B. a solid surface on which condensation can take place must be available -called a condensation nucleus (pl.: nuclei) -the troposphere has lots of these. Dust, salt etc.

6 Cloud Formation - When air cools to a temperature that is below the dew point, condensation causes clouds to form.

7 Cloud Formation - Some clouds form when one body of moist air mixes with another body of moist air that has a different temperature.

8 Cloud Formation - Air can be forced upward when a moving mass of air meets sloped terrains, such as a mountain range. -called lifting

9 Cloud Formation -The temperature of an air mass can decreases as the air mass moves over a cold surface -the cold surface absorbs heat from the air and the air cools. -if the air cools below its dew point, clouds form.

10 Fog Fog is water vapor that has condensed very near the surface of Earth because air close to the ground has cooled -Fog is a cloud at ground level (stratus type)

11 Classification of Clouds Clouds are classified by their shape and their altitude. The three basic cloud forms are stratus clouds, cumulus clouds, and cirrus clouds. There are also three altitude groups: low clouds (0-2,000 m), middle clouds (2,000 to 6,000 m), and high clouds (above 6,000 m).

12 Classification of Clouds Low clouds 1. Stratus cloud a gray cloud that has a flat uniform base and that commonly forms at very low altitudes Stratus means sheet-like or layered. Stratus clouds cover large areas of sky and often block out the sun. Usually, very little precipitation falls from most types of stratus clouds. Fog is a stratus cloud that touches the ground

13 Classification of Clouds 2. Cumulus Clouds cumulus cloud a low-level, billowy cloud that commonly has a top that resembles puffy cotton balls and has a dark bottom Cumulus means piled or heaped. These clouds form when warm, moist air rises and cools. As the cooling reaches its dew point, the clouds form. The flat base that is characteristic of most cumulus clouds represents the condensation level.

14 Classification of Clouds 3. Cirrus Clouds cirrus cloud a feathery cloud that is composed of ice crystals and that has the highest altitude of any cloud in the sky Cirro and cirrus mean curly. Cirrus clouds form at altitudes above 6,000 m. These clouds are made of ice crystals because the temperatures are low at such high altitudes. Because these clouds are thin, light can easily pass through them

15 Middle Clouds - (2,000 to 6,000 m) Start with the prefix Alto Examples: altostratus middle cloud that s flat altocumulus middle cloud that s puffy

16 High Clouds above 6000 Start with the prefix Cirro Examples: Cirrostratus high flat thin & wispy type Cirrocumulus high puffy clouds Cirrus highest of all clouds wispy ice crystals

17 Rain Clouds - precipitation Cloud name prefix: nimbo or suffux: nibus added to cloud. Nimbostratus clouds are large flat dark clouds that can cause heavy precipitation. Cumulonimbus clouds, Large, dark storm clouds known as thunderheads, are often accompanied by rain, lightning, and thunder. Have large anvil shape tops.

18 Classification of Clouds

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20 Classification of Clouds Where they are found What they look like Type of weather they bring Interesting fact nimbostratus altostratus cumulonimbus altocumulus cirrocumulus cirrostratus

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