Humidity and Condensation

This week we will discuss the characteristics of water and how it affects the atmosphere. Water is unique because it is the only substance that commonly exists in the atmosphere in each of the three states of matter. Depending on its temperature, water can either be a solid, a liquid, or a gas. When water changes from one state to another, energy is either absorbed or given off. The change from water vapor to liquid water is called condensation. Products of condensation include dew, fog, and clouds.

The amount of water vapor (moisture) in the air varies widely. The actual amount of water vapor in the air at a given point in time and place is called the specific humidity. There is a limit to the amount of water vapor that can be present in the air. When the air contains as much moisture as it can, the air is saturated. Meteorologist mostly refer to the relative humidity. This compares the actual amount of water vapor in the air with the maximum amount of water vapor that can be present in the air at a given temperature and pressure. the air's ability to hold water vapor therefore depends on the temperature and pressure in the atmosphere.

Homework # 16: Due Tuesday, June 2, 2009

Review Book: read pages 141-147. Do questions 1-15, pages 147-148.

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