Humidity Clouds Precipitation Water and Weather Humidity Clouds Precipitation

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

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

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

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

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

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)

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

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)

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

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

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

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

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

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

Measuring precipitation rain gauge ruler for snow

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 1986. 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).

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

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