CLOUDS OUTLINE I. How Do Clouds Form? A. Condensation 1. Condensation- the process by which molecules of water vapor in the air become liquid water 2. cold air can hold less water vapor than warm air 3. dew point- the temperature at which condensation begins B. Where does condensation occur? 1. solid surfaces on the ground a. above freezing- dew (water) b. below freezing- frost (ice) 2. particles in the air- clouds a. salt crystals b. dust from soil c. smoke C. Windward and Leeward sides of a mountain 1. Windward- Upward side a. Wind hits side of the mountain b. Forced upward and rises c. As it rises it cools d. Water vapor in air condenses and forms clouds e. Cool air can no longer hold water f. Rain or snow falls g. At the top of the mountain air has lost most of it’s water vapor 2. Leeward- Downward side a. Air is dry and cool b. Rain shadow is created (lack of rain) c. Air becomes warmer as it falls d. Often creates a desert II. Types of Clouds A. Cumulus 1. look like big puffy piles of cotton 2. form less than 2 km above the ground up to 18 km 3. usually indicate fair weather 4. cumulonimbus- towering clouds with flat tops that often produce thunderstorms B. Stratus 1. look like flat layers 2. cover the entire sky 3. nimbostratus- can produce drizzle, rain or snow C. Cirrus 1. wispy, feathery clouds 2. form about 6 km where it is very cold 3. made of ice crystals D. Fog 1. clouds that form near the ground 2. ground cools at night after a warm, humid day 3. The ground cools the air directly above it to the airs dew point.