WATER IN THE ATMOSPHERE

Honors Earth scienceChapter 16

Water vapor

• Is a gas• You cannot see it!!!

• What state of matter are:– Clouds?– Fog?

Give examples of water in the atmosphere

• Solids-

• Liquids-

• Gas-

Water changes state(from worksheet)

• Liquid → Solid– freezing

• Solid → liquid– melting

• Gas (water vapor)→ liquidcondensation

• Liquid → gas– evaporation

Water changes state• Gas to solid?

Deposition– Frost

– Solid to gas?– Sublimation

• Dry ice

– Most water vapor enters atmosphere through– EVAPORATION

WORKSHEET

LATENT HEAT

•la·tent heat- nounPHYSICS•the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature.

•Energy (heat) that is used during a phase change

http://jamaica.u.arizona.edu/ic/nats1011/lectures/ch05/FIG05_006.JPG

Relative Humidity

Capacity of Air is dependent on temperature

• Warm air can hold more water vapor than cold air!!

relative humidity

• Temp.= 31ºC water vapor in air= 25 g• Calculate the rh:

25/29.4= .85 x 100= 85%

85% of the air is filled with water vaporWhat happens at 100% RH?condensation!

Relative humidityuse real data

• Air temp= • Relative humidity is

• What is the water vapor content?

How do we measure water vapor content?

• Cool it until it can’t hold anymore moisture.• This temp is DEW POINT• Then use chart

Dew point• Temperature at which

100% humidity occurs• (condensation temp)

• Frost will form if DP is below freezing– Gas solid

Who cares about dew point?

• Lawn care • Sports on grass• Farmers/ Gardeners• Bad hair days?• Tell the humidity

– When air temp. is closer to dew point temp, humidity is higher

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