1. Ch 23 - Water in the Atmosphere

2. Atmospheric Moisture Changing forms of Water
Water exists in three states on Earth
Solid - ice
Liquid - water
Gas - water vapor

3. 2. Latent Heat Heat is absorbed or released when water changes phases
Water Releases Heat
Ice Water Water Vapor
Water Absorbs Heat

4. 4. Sublimation- process by which water changes phases from solid directly to gas
3. Most water enters the atmosphere through evaporation

5. B. Humidity- water vapor in the atmosphere
When water vapor is condensing at the same rate it is evaporating, the air is saturated
Dew point - the temperature at which water begins to condense faster than it evaporates

6. 3. Absolute humidity - the amount of water in the air
4. Relative humidity - the ratio of water vapor in air to amount needed to reach saturation
a. Cold air holds less humidity
b. warm air holds more humidity
5. When air is saturated, water will condense with just a small drop in temperature- air has then reached the dew point

7. C. Measuring Humidity Thin polymer film- measured with conductivity
Psychrometers
Two thermometers which are spun
Dry bulb records temperature
Wet bulb records rate of evaporation
Table is used to calculate humidity

8. Clouds are identified by for altitude and shape!
Clouds and Fog
Cloud formation
Temperatures below dew point
Condensation nuclei
Cloud Types-3 Basic Types:
Clouds are identified by for altitude and shape!
Cirrus
Cumulus
Stratus

9. Precipitation
Rain - Liquid precipitation
Drizzle - small rain drops

10. Solid Precipitation Snow Most common form of frozen precipitation
Consists of ice particles
Sleet - rain that freezes near ground
Hail - lumps of ice that form in thunderstorms by circulating in cumulonimbus clouds
Ice storms- rain that freezes when it hits the ground

11. 5. Formation Coalescence- smaller drops clumping together
Supercooling - droplets that are chilled to below freezing without turning to ice

12. C. Measuring Precipitation
Rain gauge - funnel that collects rain
Measuring stick for snow
Doppler Radar

13. D. Weather Modification - limited success
Cloud seeding - providing condensation nuclei with silver iodide