1. Title: 11.3 Clouds and Precipitation
April 15, 2014

2. Objectives
Students will be able to explain the difference between stable and unstable air.
Students will be able to compare and contrast low, middle, high and vertical development clouds.
Students will be able to explain how precipitation forms.

3. Word of the Day
Condensation: The process in which water vapor changes to a liquid.

4. 11.3 Clouds and Precipitation
Main Idea: Clouds vary in shape, size, height of formation, and type of precipitation.

5. 11.3 Clouds and Precipitation
Cloud Formation:
Clouds form when rising air masses cool.
Cooling causes water vapor to condense.

6. 11.3 Clouds and Precipitation
Condensation Nucleus: A particle in the atmosphere around which water droplets can form.
Ice
Salt
Dust
Droplets can be ice or water.
When there are a lot of droplets, clouds are visible.

8. 11.3 Clouds and Precipitation
Atmospheric Stability: As an air mass rises it cools.
Stable Air: Air that stops rising because it has cooled.
Produces fair weather clouds.
Unstable Air: Air that continues to rise because it is always less dense than the surrounding atmosphere.
Produces thunderstorm clouds.

9. P. 299 Atmospheric Lifting:
Clouds form when moist air rises and cools.
Convective Lifting:Warm, less dense air will rise.
Orographic Lifting: When an air mass is forced to rise over a topographic barrier (mountains.)
Wind forces warm air up mountain side.
When air reaches dew point, clouds form and precipitation occurs.
Convergence: Warm air collides with cold air.
Less dense warm air is forced up.
When rising air reaches dew point clouds form.

11. Classification of clouds based on 2 things:
P. 300
Types of Clouds:
Classification of clouds based on 2 things:
Altitude
Shape

13. 3 Classes of Clouds based on Altitude:
P. 300
3 Classes of Clouds based on Altitude:
Low - below 2000m
Middle - between 2000m and 6000m
High - above 6000m

14. P. 300 Low: Middle: High: Cumulous: Puffy and lumpy looking
Stratus: Layered, sheetlike, block whole sky.
Middle:
Ice and water droplets
Altocumulous: White or gray - Large round or wavy
Altostratus: Gray - Thin sheets
High:
Ice crystals
Cirrus: Whispy and indistinct
Cirrostratus: Continuous layer that covers the sky

15. Vertical Development Clouds: Rising unstable air
Cumulonimbus: Tall, Ice at top
May produce rains, winds and hail
Associated with thunderstorms