Transcript Water in the Atmosphere

Water in the Atmosphere
Objective-Explain how water gets into the
atmosphere.
Chapter 12-1 Where does water in the atmosphere come from?
Water in the air is in the form of gas called water vapor.
Water vapor is an odorless, colorless gas.
Water vapor in the air varies from place to place and over time.
Water in the atmosphere.
Evaporation- changing a liquid into a gas.
Most of the water in the air evaporates from the oceans.
Winds carry the water vapor in the air over the Earth’s surface.
Heat and Evaporation
Kinetic theory- theory that states that matter is always in motion.
Solid
Liquid
Gas
When a liquid is heated, its molecules move faster.
Evaporation occurs more rapidly in warm liquids.
Evaporation occurs most rapidly at the equator.
Living things and water vapor.
Plants also give off water vapor.
Transpiration- process by which plants give off water vapor into the air.
Transpiration occurs in the leaves of plants through tiny openings called stomata.
Chapter 12-2 What is humidity?
Objective- Explain how we measure the amount of water vapor in the air.
Humidity- amount of water vapor in a particular parcel of air.
Capacity- amount of water vapor a parcel of air can hold.
Air’s capacity for holding water vapor changes with air temperature.
Warm air has a higher capacity to hold moisture.
Cold air has less capacity to hold moisture.
Saturated- filled to capacity.
When the spaces between air molecules is filled completely with water vapor.
As an air mass cools the spaces get smaller and water vapor begins to condense.
Capacity-Saturation
When is the humidity higher? Morning or afternoon.
Humidity in the Air
Specific Humidity- actual amount of water in the air.
expressed as number of grams of water vapor per 1 kg of air.