1. Weather
Ch. 16

2. Clouds Clouds form as warm air is forced upward, expands, and cools
As the air cools, the amount of water vapor needed for saturation decreases and the relative humidity increases

3. Clouds When the relative humidity reaches 100%, the air is saturated
Water vapor begins to condense in tiny droplets around small particles such as dust and salt
Billions of these droplets form a cloud

5. Classifying Clouds Classified mainly by shape and height
Large amount of variety

6. Cloud Types
Stratus—form layers or smooth sheets in the sky

7. Cloud Types
Cumulus—masses of puffy, white clouds

8. Cloud Types
Cirrus—high, thin, white, feathery clouds

9. Cloud Height Cirro- = high clouds Alto- = middle-elevation clouds
Strato- = low elevations
Some cloud names combine the altitude prefix with the term stratus or cumulus

10. Rain and Snow Clouds
Clouds associated with rain or snow often have the word nimbus attached to them
Nimbus = dark rain cloud
Cumulonimbus
Nimbostratus