Topic: Topic: Moisture in the Moisture in the

AtmosphereAtmosphere

Water enters the Atmosphere byWater enters the Atmosphere by

A) ---A) ---

Mainly from Mainly from Ocean Ocean

70% Earth70% Earth’’s s surfacesurface

Factors Effecting Evaporation Factors Effecting Evaporation RateRate

a)a) Surface Temperature Increases Surface Temperature Increases ------

b)b) Surface Area Increases Surface Area Increases ------

Puddle A Puddle B

Evaporation Evaporation

c) Humidity increases ---

Lake

Evaporation

Air is filled with water, no more evaporation.

d) Wind Speed Increases ->---

Lake

B) ---B) ---

Evaporation and Evaporation and Transpiration = Transpiration =

EvapotranspirationEvapotranspiration

Water is found in all phases in the Water is found in all phases in the atmosphere atmosphere

1)1) Solid – Clouds, snowSolid – Clouds, snow

2)2) Liquid – Clouds, rainLiquid – Clouds, rain

3)3) Gas - Water vaporGas - Water vapor

How do we measure How do we measure

moisture in the moisture in the AtmosphereAtmosphere

HumidityHumidity

------

Relative HumidityRelative Humidity ------

------

Dew PointDew Point ------

What happens when the air What happens when the air temperature and dew point are the temperature and dew point are the same?same?Condensation

Sublimation / DepositionSublimation / Deposition

FROST

SNOW

Tools used to find Dew Point & Relative HumidityTools used to find Dew Point & Relative Humidity

--- ---

------

Measuring Relative HumidityMeasuring Relative HumidityToday you need your ESRT outToday you need your ESRT out

Dew Point & Relative Dew Point & Relative Humidity ChartsHumidity Charts

Best Friend - pg 12Best Friend - pg 12

The The ““Dry BulbDry Bulb”” = Air Temp = Air Temp

DonDon’’t let it fool you. It t let it fool you. It is just a thermometer.is just a thermometer.

20°C

The The ““Wet BulbWet Bulb”” Has a little wet Has a little wet

booty tied to the booty tied to the bottom.bottom.

Gets cool when Gets cool when water evaporates.water evaporates.

12°C

Wet Booty

A Dry Day…A Dry Day…

A lot of A lot of moisture will moisture will evaporate.evaporate.

The wet bulb The wet bulb will be a lot will be a lot cooler than the cooler than the dry bulb.dry bulb.

8°C

20°C

Difference between wet bulb & dry bulb is 12 °C.

20°C14°C12°C

A Humid Day…A Humid Day…

A little bit of A little bit of moisture will moisture will evaporate.evaporate.

The wet bulb The wet bulb will not be will not be much cooler much cooler than the dry than the dry bulb.bulb.

14°C

20°C

Difference between wet bulb & dry bulb is 6 °C.

Dry-bulb temperature = air temperature.

20 °C

14 °C

Subtract (the difference) between the dry bulb and wet bulb

14°C20°C

20-14=6

16°C18°C

18-16=2

8°C20°C

20-8=12

Put it all together

Relative Humidity = 11%

10°C14°C

14-10=4

Relative Humidity = 60%

10°C14°C

14-10=4

Dew Point = 6°C

The Dew Point Chart works the same way

Try These.Try These.Dry BulbDry Bulb Wet BulbWet Bulb R R

HumidityHumidityDPTDPT

26°C26°C 20 °C20 °C

14 °C14 °C 14 °C14 °C

0 °C0 °C -3 °C-3 °C

% °C°C

% °C°C

% °C°C

Dry BulbDry Bulb Wet BulbWet Bulb R R HumidityHumidity

DPTDPT

21°C21°C 19°C19°C

17 °C17 °C 17°C17°C

70°F70°F 60 °F60 °F

% °C°C

% °C°C

% °C°C °C°C °C°C