1 Air, Weather, and Climate. 2 2 Earth’s Atmosphere Compared to the size of the Earth (12000 km), the atmosphere is a thin shell (120 km) Composed.

1

Air, Weather, and ClimateAir, Weather, and Climate

222

Earth’s AtmosphereEarth’s Atmosphere

Compared to the size of the Earth (12000 km), the atmosphere is Compared to the size of the Earth (12000 km), the atmosphere is a thin shell (120 km)a thin shell (120 km)Composed of:Composed of:

– ~78% N~78% N22 gas gas

– 21% O21% O22 gas gas

– 1% argon gas and other permanent gases1% argon gas and other permanent gases

333

If the Earth is If the Earth is compared to compared to

thisthis Orange… Orange…the Earth’s the Earth’s atmosphere atmosphere would be would be

thinner than thinner than the layer of the layer of pesticide onpesticide on

this Orange’s this Orange’s surfacesurface

4

Layers of the AtmosphereLayers of the Atmosphere

TroposphereTroposphere StratosphereStratosphere MesosphereMesosphere ThermosphereThermosphere IonosphereIonosphere ExosphereExosphere

5

TroposphereTroposphere

Closest to the earth’s surfaceClosest to the earth’s surface Where we liveWhere we live

– Weather occurs hereWeather occurs here very thin (averaging 11 km or 7 miles high)very thin (averaging 11 km or 7 miles high) Densest layerDensest layer

– Most of nitrogen, oxygen and water vapor hereMost of nitrogen, oxygen and water vapor here

Temp decreases as altitude increasesTemp decreases as altitude increases

6

StratosphereStratosphere

Above the troposphereAbove the troposphere extends to 50 kilometers (31 miles) highextends to 50 kilometers (31 miles) high dry and less densedry and less dense UV rays reach higher altitudes and warm themUV rays reach higher altitudes and warm them Ozone layerOzone layer

7

MesosphereMesosphere

extends to 85 kilometers (53 miles) highextends to 85 kilometers (53 miles) high temperature decrease with altitude reaching temperature decrease with altitude reaching

-90-90°°C at the topC at the top

8

ThermosphereThermosphere

extends to 600 kilometers (372 miles) highextends to 600 kilometers (372 miles) high temperatures go up as altitude increases due to temperatures go up as altitude increases due to

absorption of solar radiation by oxygenabsorption of solar radiation by oxygen molecules so few and far between that they molecules so few and far between that they

collide rarelycollide rarely Farthest away from earth’s surfaceFarthest away from earth’s surface

9

IonosphereIonosphere

Within the thermosphereWithin the thermosphere Contains ions when hit by solar energy begin to Contains ions when hit by solar energy begin to

glow and produce lightglow and produce light– Aurora BorealisAurora Borealis

reflects many types of radio waves allowing reflects many types of radio waves allowing them to bounce around the worldthem to bounce around the world

10

ExosphereExosphere

Top of the thermosphere and continues until it Top of the thermosphere and continues until it merges with interplanetary gases, or space (372 merges with interplanetary gases, or space (372 to 6200 miles)to 6200 miles)

11

Seasonal ChangesSeasonal Changes

Occurs due to Occurs due to earth’s axis being earth’s axis being tiltedtilted

Creates opposite Creates opposite seasons seasons

Factor that Factor that determines global determines global air circulation air circulation patternspatterns

12

SeasonsSeasons Seasons are short periods Seasons are short periods

of climatic change.of climatic change. Certain areas receive Certain areas receive

changing amounts of changing amounts of radiation throughout the radiation throughout the yearyear

13

Earth’s SeasonsEarth’s Seasons

North Pole

Earth

SUMMER (Northern Hemisphere)

South Pole

WINTER (Southern Hemisphere)

Equator

14

Tilt of the Earth’s axis towards or away from the sun creates the seasons

Earth’s Seasons Continued….Earth’s Seasons Continued….

Earth

WINTER (Northern Hemisphere)

SUMMER (Southern Hemisphere)

North Pole

South Pole

Equator

15

WeatherWeather WeatherWeather – daily temperature and moisture – daily temperature and moisture

conditions in a placeconditions in a place– driven by atmospheredriven by atmosphere– atmospheric conditions over short time periods (hours atmospheric conditions over short time periods (hours

or days) in small geographic areasor days) in small geographic areas– produced by interacting air massesproduced by interacting air masses– Types of weatherTypes of weather

Warm Front-warmWarm Front-warm air displaces cool airair displaces cool air Cold Front-cooler air displaces warmer air Cold Front-cooler air displaces warmer air Severe-hurricanes, thunderstorms, tornadoesSevere-hurricanes, thunderstorms, tornadoes

16

WeatherWeather

Contribute to WeatherContribute to Weather– Air temperature Air temperature

– Air pressure Air pressure

– Humidity Humidity

– Cloud cover Cloud cover

– Precipitation Precipitation

– Winds Winds

17

Air TemperatureAir Temperature As solar energy reaches the equator, regions heat As solar energy reaches the equator, regions heat

up more than the poles. up more than the poles. Warm air and water at the equator travel toward Warm air and water at the equator travel toward

the poles while cold air and water at the poles the poles while cold air and water at the poles travel toward the equator in an attempt to travel toward the equator in an attempt to equalize the temperature equalize the temperature – Constant struggle = changing weather Constant struggle = changing weather

18http://www.usatoday.com/weather/tg/wglobale/wglobale.htm

19

Air PressureAir Pressure Caused by the weight of air pressing down on the EarthCaused by the weight of air pressing down on the Earth

High pressure-cool, dense air that descends towards High pressure-cool, dense air that descends towards surface of earthsurface of earth– Fair weatherFair weather

Low pressure-less dense warm air goes toward the Low pressure-less dense warm air goes toward the center of a low pressure air masscenter of a low pressure air mass– Produces cloudy and stormy weatherProduces cloudy and stormy weather

Air pressure changes with weatherAir pressure changes with weather

20

21

Humidity and Cloud CoverHumidity and Cloud Cover

Relative humidity-Relative humidity-amount of water vapor in the air amount of water vapor in the air Cloud CoverCloud Cover

– clouds cool the planet by reflecting sunlight clouds cool the planet by reflecting sunlight AlbedoAlbedo

– reduces the amount of heat that radiates into space reduces the amount of heat that radiates into space

22

WindsWinds

Speed is determined by differences in pressureSpeed is determined by differences in pressure Coriolis effect Coriolis effect

– Deflection of objects moving in a straight path Deflection of objects moving in a straight path relative to the earth’s surfacerelative to the earth’s surface

– Proportional to the speed of the earth’s rotation at Proportional to the speed of the earth’s rotation at different latitudesdifferent latitudes as latitude increases and the speed of the earth’s rotation as latitude increases and the speed of the earth’s rotation

decreases, Coriolis effect increasesdecreases, Coriolis effect increases

23

Winds cont.Winds cont.

Hadley cellsHadley cells– Solar energy warms humid air in tropicsSolar energy warms humid air in tropics– Warm air rises, cools, condenses and precipitatesWarm air rises, cools, condenses and precipitates– Dry air sinks and is warmed Dry air sinks and is warmed

Hot dry air causes desertsHot dry air causes deserts

24

25

26

Convection CurrentsConvection Currents