1. Ch. 2 Sec. 4 Water in the Atmosphere

2. OBJECTIVE: Describe types of precipitation and Humidity and explain how they are measured.

3. 1.Water Cycle: The movement of water between the Atmosphere and Earth’s surface. 2.Evaporation: The Process by which water molecules in liquid water escape into the air as water vapor. 3.Humidity: The measure of the amount of water vapor in the air. 4.Relative Humidity: The percentage of water vapor in the Air compared to the maximum amount the air can hold. It is Measured with a Psychrometer. 5, Psychrometer: Has two thermometers, a wet bulb and a Dry bulb.

4. 6.Clouds of all kinds form when water vapor in the air becomes liquid water or ice crystals. 7.Condensation: Process by which molecules of water Vapor in the air become liquid water. 8.Dew Point: The temperature at which condensation Begins. 9.Scientists classify clouds into 3 main types based on their Shapes: Cirrus, Cumulus, and Stratus. Clouds are further Classified by their altitude. 10.Cirrus Clouds: Wispy, feathery - Means “curl of hair” – Form above 6KM so they are made of ice crystals

5. 11.Cumulus Clouds: Fluffy, rounded piles of cotton – Cumulus means “Heap” or “Mass” – Form at less than 2 KM And extend up as much as 18 KM 12.Stratus Clouds: Flat layers of clouds – Strato means “Spread out” - 13. Fog: Clouds that form at or near the ground.