Title: 11.3 Clouds and Precipitation April 15, 2014

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.

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

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

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

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.

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.

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.

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

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

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

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