18.1 Made up of mainly two gases: – Nitrogen 78% – Oxygen 21% – Trace Gases 1%

THE ATMOSPHERE

18.1

The Atmosphere Made up of mainly two

gases:–Nitrogen 78%–Oxygen 21%–Trace Gases 1%

Layers of the Atmosphere

made up of 5 layers:–Troposphere–Stratosphere–Mesosphere– Ionosphere–Thermosphere

1. Troposphere The atmospheric layer we live in. Almost all weather occurs here. Contains water vapor and oxygen. Highest density Temps decrease as you increase

altitude until you reach the top of the layer called the tropopause.

Troposphere Within the troposphere a

temperature inversion may occur. This is a condition where warmer

air traps cooler air near the Earth’s surface.

This can cause air to get thick with pollution, where it can’t escape.

Temperature Inversions

2. Stratosphere– Lacks O2 and water vapor. (no weather)

– Contains the ozone (O3) layer. (this layer absorbs solar UV radiation)

– Temperatures increase as you gain altitude.

– Higher altitude than most aircraft would fly

Stratosphere

3. Mesosphere–The coldest of layer of the atmosphere. (-800C)

–Temperature decreases with altitude

4. Ionosphere Consists of upper mesosphere and lower

thermosphere. Contains charged ions that reflect radio waves

allowing transmissions to travel great distances.

Radio waves will travel farther at night than during the day. (less ions)

Where the aurora borealis can be seen. (excited photons)

Aurora Borealis – Northern lights

5. Thermosphere Most outer layer. Hottest layer (9800C) temperatures will increase with increase altitude

It absorbs solar radiation

Early Atmosphere Early atmosphere was much

different during Earth’s early days.

Volcanic eruptions released H2, ammonia, methane. CO, CO2 and N2.

No oxygen was present

Changing Atmosphere

Around 2.5 billion years ago single celled organisms evolved to capture the suns energy and CO2 to start the photosynthesis process

Then plants began appearing releasing oxygen into the atmosphere.

Present Atmosphere 350 million years later aerobic

organisms came along and balanced the atmosphere.

They took in oxygen and released carbon dioxide as a by product during respiration.

And thus the O2 and CO2 cycle was created.

Carbon Dioxide/ Oxygen Cycle

Our effect on the atmosphere.#1 Natural Stratosphere Ozone

Protects us from UV radiation. Can be destroyed by

chlorofluorocarbons or CFC’s Used during 1950s thru 1980s

in refrigerators and spray cans. CFCs are now banned in most

countries Ozone layer is repairing itself

#2 Man-made Ozone Ozone while helpful in stratosphere, is very toxic if trapped in the troposphere.

Main gas pollutant from cars, trucks, factories that causes smog.

Ozone Issues:

Greenhouse effect The process by which the

atmosphere traps some of the energy from the sun in the troposphere.

CO2, water vapor, and other gases absorb the suns energy (greenhouse gases)

Keeps the planets climate balanced

#3 Enhanced Greenhouse Effect

We are adding more and more CO2 and other greenhouse gases into the atmosphere:– Forest fires and volcanoes– Air Pollution from fossil fuel burning

– Increasing human population– Decrease in plant life and rain forest

– Increase of cattle grazing

Melting Ice Caps

Artic Ice Shelf

Melting Glaciers

Rising Sea levels

Increasing Extreme Weather Events

WATER AND WIND

18.2

The Water Cycle The continuous movement of water from atmosphere to Earth and back.

4 mechanisms of travel

The Water Cycle Water enters the

atmosphere:1.Evaporation

Evaporation occurs at the lakes, rivers, and oceans.

2.Transpiration evaporation of water through plant’s leaves.

Transpiration

The Water CycleWater Exits: 3. Condensation

Water vapor rises until it is cool enough to condense to form clouds.

4. Precipitation When the cloud become full of

water droplets they will release moisture back down to Earth in the form of rain, sleet, ice, or snow.

Condensation

Evaporation

Water Vapor Water vapor is always in the air Humidity

– The quantity/amount of water vapor in the atmosphere

Relative humidity (percentage)– is the actual amount of water in the atmosphere compared to maximum amount it can hold.

The higher the temperature, the more water that can be held in the air.

Dew Point The temperature at which

water vapor molecules start to form liquid water.

Higher the humidity the higher the dew point.

dew point

Clouds Made up of tiny condensed droplets of liquid water.

3 main types

1. Cirrus Clouds highest altitude clouds

appear wispy and light.

Cirrus Clouds

2. Stratus Clouds layered or sheet like clouds

form at lower altitudes.

Stratus Clouds

3. Cumulus Clouds white and fluffy appear at many levels.

Cumulus Clouds

Other Clouds Other clouds are a

combination of the 3 cloud types.

The root nimbus means the cloud contains precipitation. (grayer color)

Ex. cumulonimbus produce thunderstorms

Nimbostratus

Cumulonimbus

Air pressure (Barometric Pressure)

The pressure due to the weight of the atmosphere.

Measured with an instrument called a barometer.

Air pressure decreases with altitude in the troposphere

Mercury Barometer

Wind Caused by differences in air

pressure between air masses. The greater the difference

the stronger the wind. Air always flows from high

pressure to low pressure– Pressure inside a plane is greater, so air would be sucked out if a window broke

Cabin Pressure

CORIOLIS EFFECT

Wind and the Earth Coriolis effect.the change in direction of an object’s path due to Earth’s rotation.

Wind and the Earth Winds in the Northern hemisphere curve right.

Winds in the southern hemisphere curve left.

WEATHER AND CLIMATE

18.3

Weather The condition of the

atmosphere at any given time

Weather is caused by traveling air masses.–Large bodies of air with the same general characteristics throughout.

Fronts A boundary where two air masses with different densities meet.

Fronts cause precipitation, change in temperature, and a change in wind direction.

Front Types Warm front-warm air moves over cooler air forming clouds.

-Produces steady rain or snow for a couple of days.

Cirrus and cirrostratus clouds

Front Types Cold fronts-Cold air moves under slow moving warm air

-Brings high winds, thunderstorms, and possible tornadoes.

Cumulonimbus clouds

WARM/COLD FRONTS

Stationary Front

Two air masses meet Neither is displaced Air masses move side by

side Similar to warm front

weather

Weather Events 1. Thunder Storms

Lightening is caused by a build up of electrical charges from water droplets and ice crystals in clouds.

When opposite charges are found on the ground or other clouds, lightening strikes.

Thunder is the sound of lightening.

Thunder Storm Safety

If you count to 10 or less after seeing lightning before hearing thunder, then the storm is less than two miles away.

2. Tornadoes Form during severe

thunderstorms. Form from cool air from the

north, and warm air from south.

Tornadoes begin as a funnel cloud that intensifies until it touches ground

Most violent winds on Earth 310mi/hr

Most common in the Midwest

3. Hurricanes Very large storms with high

winds. Also known as cyclones and

typhoons Form in the tropics Created by rising warm water

vapor from warm ocean water. Then powered by the energy

released from water vapor condensing into clouds

Weather maps Produced by meteorologists to help

forecast weather. They use many variables

–Precipitation and cloud cover–Wind speed-Air pressure (isobars)– fronts

Climate Average weather

condition over many years for a particular region.

It is not measured day by day.

Climate Affected By:

1. Latitude (closeness to equator) Angle at which the sun hits Earth

2. Cycling of seasons and season Length

The tilt of the earth’s axis as it travels a revolution around the sun is the reason that we have seasons.

3. Yearly rainfall4. Topography (type of land)

Elevation, amount of water, mountains or flatness