The Journey of Flight.pdf - Valkyrie Cadet

Chapter Chapter 18 18 18 - - The The Atmospher Atmospher Atmosphere
Atmospher Atmospher
Evaporation Cycle
Humidity and Relative Humidity. Invisible vapor is the water form usually associated with
humidity. While there are many ways of explaining humidity, the simplest approach begins by emphasizing
that
1. temperature is the main cause of humidity and precipitation,
2. before precipitation can occur, there must be enough water vapor present,
3. the amount of water vapor the air is able to hold depends on the temperature of the air,
4. warm air can hold more water vapor than cold air, and
5. as air cools, its ability to hold water vapor decreases.
This chart shows relative humidity and temperature. When RH is 100% at a given temperature, the dew point is
reached. It also shows that the ratio of A to B equals relative himidity and indicates how far away from saturation the
unit of air is (C).
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