Chapter 23 Moisture in the Atmosphere

1. Chapter 23 Moisture in the Atmosphere Condensation

2. Review Points • Condensation- Changing of a gas to a liquid. • Types of condensation Fog- condensation at or near the earth’s surface. Radiation fog- fog that develops when the earth’s surface cools and the moist air above the surface condenses. Also known as ground fog. Advection fog- fog created when winds blow moist air over a cool surface. Frost- condensation that forms on a frozen surface. Dew- liquid condensation that forms on a cool surface. Dew Point- temperature to which air must be cooled to reach saturation.

3. Chapter 23 Condensation and Clouds Clouds- condensation that occurs above the earth’s surface when gas vapor cools and forms tiny microscopic liquid droplets or ice crystals. • Gas vapor must cool to form cloud droplets. Gas vapor cools by moving upwards in the troposphere. • A clouds shape, composition and characteristics is determined by how it forms. • Condensation Nuclei- microscopic particles in which condensation forms to create cloud droplets. (i.e.) smoke, dust, pollen, ash, sea salt, smog • Types of clouds: Cirrus cloud- light, feathery cloud. Cumulus cloud- big, puffy cloud, which forms vertically. Stratus cloud- sheetlike cloud that forms horizontal layers. Alto- Middle layer clouds. Nimbo- stratus clouds that has precipitation falling from them. Nimbus- cumulus clouds that has precipation falling from them.

4. Cirrus • Made from ice crystals, very high. Cirrus Cirrostratus

5. Stratus Stratus- horizontally forming cloud, forms in layers. Stratus Nimbostratus

6. Cumulus Vertically forming cloud. Cumulus Cumulonimbus

7. Chapter 23 Precipitation Precipitation- water that falls from the atmosphere. * When air becomes saturated, moisture coalescences, and falls from a cloud. Coalescence- when tiny, liquid, cloud particles collide and fall to the earth. Types of precipitation: Rain droplets- liquid precipitation that falls to the earth, varies in size. Drizzle- smallest of the rain droplets. Snow- six-sided crystal that falls as a solid form of precipitation. Sleet- partially frozen raindrop. Formed when liquids fall through a extremely cold layer near the earth’s surface. Hailstone- Onion shaped, frozen raindrop that falls from a cumulonimbus cloud Rain gauge- device used to measure precipitation. Cloud seeding- adding artificial condensation nuclei to a moist mass of air or cloud to produce precipitation.

8. Types of Precipitation Rainfall Snow

9. Hailstone Structure Shape Size

10. Where does it rain? • Latitudinal Rainfall- When air rises it cools, condenses and falls to the earth as rain or snow. • Convectional- When warm air rises in the hot desert regions, cools, condenses and begins to precipitate.

11. Where does it rain? • Orographic- moist air is forced up a topographic feature, cools, condenses and begins to precipitate. • Frontal- Cold air moves into a region of warm moist air, causing it to rise, cool and precipitate.