Book I, Chapter 1Book I, Chapter 1“The Atmosphere”“The Atmosphere”

Section 1, pages 4-9Section 1, pages 4-9

““Characteristics of the Characteristics of the Atmosphere”Atmosphere”

Atmosphere – A mixture of Atmosphere – A mixture of gases that surrounds the gases that surrounds the Earth.Earth.Composition of the Atmosphere: Gases:Gases:

78% Nitrogen78% Nitrogen

21% Oxygen21% Oxygen

1% Argon, CO1% Argon, CO2, 2,

Water Vapor &Water Vapor &

other Gasesother Gases Small amts. of Solids Small amts. of Solids

& Liquids (ex. dust)& Liquids (ex. dust)

Air Pressure – A measure of the Air Pressure – A measure of the force with which the force with which the molecules push on a surface.molecules push on a surface.What causes air What causes air

pressure?pressure?

Air pressure is Air pressure is caused as caused as gravity pulls gravity pulls molecules in molecules in the the atmosphere atmosphere toward the toward the Earth.Earth.

Example of Air PressureExample of Air Pressure

Popping of your Popping of your earsears. As an airplane . As an airplane goes up and down at goes up and down at different elevations different elevations the air pressure the air pressure outside your ears outside your ears changes, but the changes, but the pressure inside your pressure inside your ears stays the same.ears stays the same.

Altitude – The height of an Altitude – The height of an object above the Earth’s object above the Earth’s surface.surface. Gravity pulls the Gravity pulls the

molecules toward the molecules toward the Earth’s surface.Earth’s surface.

The farther away The farther away from the Earth’s from the Earth’s surface, the pressure surface, the pressure decreases.decreases.

Altitude Altitude = = Pressure Pressure

Up DownUp Down

Layers of the Atmosphere –Layers of the Atmosphere –4 layers based on 4 layers based on temperature.temperature.

1. Troposphere (1. Troposphere (tropotropo means means “change”)“change”)

Lowest layer of atmosphere (closest to Earth) Lowest layer of atmosphere (closest to Earth) Weather take place hereWeather take place here Begins at surface of Earth & extends out 4-10 Begins at surface of Earth & extends out 4-10

milesmiles Layer where we live also known as lower Layer where we live also known as lower

atmosphereatmosphere Temperature decreases with heightTemperature decreases with height

2. Stratosphere (2. Stratosphere (strato means strato means “layer”)“layer”) Above the troposphereAbove the troposphere Air very thin w/ little moistureAir very thin w/ little moisture Extends 30-35 miles above Earth’s surfaceExtends 30-35 miles above Earth’s surface Temperature rises w/ increasing altitude, but Temperature rises w/ increasing altitude, but

still still well below freezingwell below freezing Ozone layer located here Ozone layer located here

OzoneOzone – made of 3 oxygen atoms & – made of 3 oxygen atoms & absorbs solar energy in form of UV rays in absorbs solar energy in form of UV rays in the ozone layer. This warms the air & the ozone layer. This warms the air & protects life on the Earth’s surface.protects life on the Earth’s surface.

3. Mesosphere – (3. Mesosphere – (meso means meso means “middle”)“middle”) Above the stratosphereAbove the stratosphere About 35-50 miles above surface of the EarthAbout 35-50 miles above surface of the Earth Coldest layer w/ temps as low as -93Coldest layer w/ temps as low as -93º Cº C Air is thin and molecules are very far apartAir is thin and molecules are very far apart Strong wind stormsStrong wind storms

4. Thermosphere – (4. Thermosphere – (thermo meansthermo means “heat”)“heat”)

The uppermost layerThe uppermost layer From 50-400 miles above surface of the EarthFrom 50-400 miles above surface of the Earth Temp increases w/ height as high as 1,700Temp increases w/ height as high as 1,700º º CC Doesn’t feel hot b/c air particles are too far apart Doesn’t feel hot b/c air particles are too far apart

for energy to be transferredfor energy to be transferred

Air Temperature & Air Temperature & AltitudeAltitude

Air temperatures change as altitude Air temperatures change as altitude increases. increases.

Temperature changes mainly from Temperature changes mainly from the way solar energy is absorbed as the way solar energy is absorbed as it moves downward through the it moves downward through the atmosphere.atmosphere.

Some gases in the atmosphere Some gases in the atmosphere absorb solar energy more than absorb solar energy more than others, and warm the atmosphere.others, and warm the atmosphere.

What does air pressure, What does air pressure, temperature, and layers of the temperature, and layers of the atmosphere have to do with atmosphere have to do with weather?weather?1. Areas of high pressure usually have clear 1. Areas of high pressure usually have clear

skies, and areas of low pressure usually skies, and areas of low pressure usually have clouds. have clouds.

2. Our weather takes place in the lower layer 2. Our weather takes place in the lower layer of the atmosphere called the troposphere.of the atmosphere called the troposphere.

3. The movement of air tends to blow from 3. The movement of air tends to blow from high pressure to low pressure areas.high pressure to low pressure areas.

4. Changes in temperature lead to changes in 4. Changes in temperature lead to changes in air pressure, bringing different kinds of air pressure, bringing different kinds of weatherweather..

Made by Mrs. VilloneMade by Mrs. VilloneAustintown Middle SchoolAustintown Middle School

Credits given to Holt, Credits given to Holt, Rhinehart and Winston Rhinehart and Winston

Science Textbook Company Science Textbook Company