1. Humidity Clouds Precipitation
Water and Weather
Humidity
Clouds
Precipitation

2. Weather is affected by the amount of water in the air.
Don’t forget
transpiration.

3. Humidity the amount of water vapor (moisture) in the air
warm air can hold more moisture

4. Relative Humidity
Relative Humidity (%)=amount of moisture in the air compared to how much moisture the air can hold (100%=saturated)
evaporational cooling
use psychrometer and chart
2 thing affect RH
amount of water vapor
temperature—RH decreases as the temperature rises and RH increases as temperature drops

5. EX: If the dry bulb reads 10°C,
& the difference between the wet
& dry-bulb thermometers is 8°C,
what is the RH? ____%

6. Condensation gas (water vapor) COOLS and becomes a liquid
air must be saturated (RH=100%)
Dew Point (measure as class activity—using jar, water, ice and thermometer)
temperature where condensation occurs
this is the temperature that dew and frost forms and the temperature where fog/clouds form

7. Cloud Formation
Cloud droplets are made of LIQUID water droplets and/or ice crystals
in order for clouds to form you need
1. moisture (water vapor)
2. cooling (to dew point)
3. particles---condensation nuclei (smoke, dust, etc)

8. Cloud types (classified by height and appearance) E-activity: Types of Clouds
Face in the clouds (website)

9. 3 main types of clouds— classified according to shape and height
Cumulus
puffy with flat bottom
form when warm air rises
can result in showers
may develop into cumulonimbus clouds (CB)= T-storm
Cirrus
thin, wispy, feathery, white clouds
form at top of troposphere (so icy)

10. 3 main types of clouds Stratus form in smooth, flat layers
blanket a large area of the sky (usually gray)
called nimbostratus if precipitating (long periods of drizzle or snow)
called fog if formed at/near the ground
other clouds
nimbo means producing precipitation
alto- means middle altitudes
contrails=make by airplanes’ exhaust

12. Websites a. Types of clouds (with pictures) b. Cloud pictures:
c. More cloud pictures (as time permits):
d. Cloud matching game --if time permits:

13. Precipitation 5 types of precipitation Rain/drizzle Snow
Sleet (also called ice pellets)
Hail
Freezing rain/freezing drizzle

14. SNOW water vapor changes directly to a solid (sublimation)
SNOW was NEVER rain

15. HAIL balls of ice that fall from thunderstorms
each trip up and down is a layer
hail forming (animated website)

16. Sleet/ice pellets —forms when rain falls through a thick layer of freezing air
Freezing rain— rain freezes right when it hits (layer of ice)—VERY dangerous

17. Measuring precipitation
rain gauge
ruler for snow

18. Did you know…
About 78% of all precipitation falls over Earth’s oceans (WHY?). Of the 22% that falls on land, about 65% returns to the air by evaporation.
The largest hailstone ever recorded fell in Bangladesh in It weighed over 1 kg.
*Arica, Chile has an average rainfall of less than 1 mm a year (.76 mm)
Kauai, Hawaii has average rainfall of 12 meters a year (keep in mind that Atlanta gets an average of 1.3 meters per year).

19. Funny?? What is a king’s favorite kind of precipitation?
HAIL
What do you get when you cross a snowman with a vampire?
frostbite
What do you call it when it rains chickens and ducks?
Foul weather

20. Websites Weather Maker simulation
Cloud Tutorial PowerPt (about 10 min—needs sound): if time permits
Weather Eye Simulation (optional)