PRECIPITATIONPRECIPITATION

HONORS EARTH SCIENCEHONORS EARTH SCIENCE

Pages 459-464Pages 459-464

PRECIPITATIONPRECIPITATION

•Any moisture that Any moisture that falls from the skyfalls from the sky

DEVELOPMENT OF PRECIPITATIONDEVELOPMENT OF PRECIPITATION

• Water Vapor(condenses)Water Vapor(condenses)→ cloud → cloud droplet → coalescence → too heavy→FALL droplet → coalescence → too heavy→FALL → precipitation→ precipitation

• Coalescence- drop collides with smaller drops Coalescence- drop collides with smaller drops and they combineand they combine

Title this diagram

Rain drop shapesRain drop shapesX

Forms of precipitationForms of precipitation

•RainRain–LiquidLiquid–.5-5 mm.5-5 mm–DrizzleDrizzle

•≤ ≤ .5 mm.5 mm

FORMS OF PRECIPITAIONFORMS OF PRECIPITAION

•SNOWSNOW– Solid Solid

•Plates or columnsPlates or columns

•Six sided flakesSix sided flakes

•1”rain=10”snow1”rain=10”snow(generally)(generally)

FORMS OF PRECIPITAIONFORMS OF PRECIPITAION

• SleetSleet– Ice pelletsIce pellets

– Melting layer wedged between 2 freezing Melting layer wedged between 2 freezing layerslayers

ground

Above 32 Fmelts

sleetBelow 32 F

snow

sleetsleet

Sleet- season?Sleet- season?

Sleet picturesSleet pictures

FORMS OF PRECIPIATIONFORMS OF PRECIPIATION

• GLAZE (freezing GLAZE (freezing rain)rain)– Rain freezes Rain freezes

when it hits cold when it hits cold surfacessurfaces

FORMS OF PRECIPIATIONFORMS OF PRECIPIATION

•HAILHAIL• Forms in Forms in

cumulonimbus cloudscumulonimbus clouds

• Gets “stuck” in cloudGets “stuck” in cloud

• Every trip up the Every trip up the cloud adds a layer of cloud adds a layer of iceice

• Season?Season?

Hail picturesHail pictures

RADAR RADAR

• Sends signal out (microwaves) and Sends signal out (microwaves) and bounces off bounces off precipitation precipitation

Radar towersRadar towers

Radar mapsRadar maps

Radar mapsRadar maps

6:32 PM GMT on November 27, 2011

GMT (Greenwich mean GMT (Greenwich mean time)time)

• - 5 hours for EST- 5 hours for EST

• Uses military timeUses military time

• Example- 2:00 GMT MI time?Example- 2:00 GMT MI time?

FOGFOG

• Not precipNot precip

• ““Ground clouds”Ground clouds”– Need same Need same

conditionsconditions

• Usually forms from Usually forms from warm ground and warm ground and colder aircolder air

Lake Effect SnowLake Effect Snow

• When cold air When cold air travels over warm travels over warm waterwater

• Snow falls on Snow falls on downwind shoredownwind shore