LAYERS OF THE ATMOSPHERE - GRADE 7scientech7.weebly.com/uploads/5/1/3/7/5137090/atmosphere.pdfWhy is...

L AY E RS O F T H E AT MO SP HE RE

Atmosphere

Why is the atmosphere divided into 5 different layers?

The atmosphere is divided into five different layers

because the atmosphere is not uniform, its

properties change with altitude.

Two properties change with altitude, the AIR

PRESSURE and the AIR TEMPERATURE

Lets look at each layer individually.

ATMOSPHERE

The earth is surrounded by a

blanket of air that we call

atmosphere. The atmosphere

is considered in terms of layers, or regions, arranged

like spherical shells above the

surface of the Earth.

COMPOSITION OF THE ATMOSPHERE

The atmosphere is primarily composed

of nitrogen (N2, 78%), oxygen (O2,

21%), and argon (Ar, 1%). A

myriad of other very influential

components are also present which

include the "greenhouse" gases or ozone (0 -

0.01%), carbon dioxide (CO2,

0.033%).

LAYERS OF THE ATMOSPHERE

There are 4 layers in the atmosphere

They are the troposphere, mesosphere, thermosphere, and stratosphere

TROPOSPHERE

This is the layer that is closest to the

surface of the earth

It’s elevation ranges from 0 to 10 km

This is where all plants and animals

live and breathe

Where weather takes place

Air is mixes

Temperature decreases with

altitude

Ozone Layer

•Pale blue gas with a strong odor.

•90% of all ozone is found in the stratosphere

•10% is found in the troposphere

•Ozone is extremely important because it is

the only gas that absorbs ultraviolet

radiation from the Sun and protects the

surface of the Earth and people from the damaging effects of

UV rays

Stratosphere

This layer sits on top of the

troposphere

It’s elevation ranges from 10 km

to around 25 km

This layer contains the ozone layer, which protects us

from harmful sunlight

People can not breathe in this

layer.

MESOSPHERE

This layer is above the stratosphere.

It’s elevation ranges from 25 to 100 km

Temperature decreases with altitude

This is where we see "falling stars" – meteors burning up as they fall

to Earth

The mesosphere is the coldest layer of the

atmosphere.

Radio waves are reflected back to earth

in the mesosphere.

Ionosphere

An extension or a part of the

thermosphere. So technically, the

ionosphere is not another

atmospheric layer.

Free electrons and ions tend to recombine

THERMOSPHERE

This is the highest layer of

the atmosphere

It’s height ranges from 100

to 400 km

This is where most small

meteorites burn up and is

also the location in the

atmosphere that the

northern lights occur

(aurora borealis)

Layer of the atmosphere

which is first exposed to

the Sun's radiation and so

is first heated by the Sun.

The air is very thin

The temperature

dependent on solar activity.

Exosphere

Highest layer of the atmosphere. The air is very

thin here

Atoms and molecules

escape into space

Label the layers of the atmosphere below:

1.TROPOSPHERE- contains dust, moisture, weather.

2.STRATOSPHERE - contains protective ozone

3. MESOSPHERE- coldest layer

4. THERMOSPHERE- contains auroras, high temperature but low heat

5. EXOSPHERE-

The highest layer of the atmosphere where commercial satellites are located.

Weather & Climate

Weather & Climate Definitions

Weather- “the state of the atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness”.

Climate – “the average course or condition of the weather at a place usually over a period of years as exhibited by temperature, wind velocity, and precipitation”

What causes Weather?

All elements of weather are the direct result of energy from the sun.

The sun’s rays hit earth and the land absorbs the heat unevenly.

This uneven heating causes changes in weather.

What does weather include?

Air temperature

Cloud cover

Amount of sunlight

Relative humidity

Precipitation

Wind speed

Wind direction

Temperature

Temperature is amount of heat in a substance. Expressed in degrees Fahrenheit or Centigrade

(Celsius)

Temperature is measure by an instrument called a thermometer.

A Bunch of Hot Air.

Cold air contracts or sinks.

The air molecules get closer together, which makes the air heavier or more dense.

Hot air expands or rises. The molecules get further apart, become less dense and they get lighter.

Air Circulation

Since warm air rises, the upper part of the room is the warmest. The coolest part of the room would be closer to the floor.

Wind Spiral

Why is the spiral able to turn?

The hot air “rising” is turning the spiral.

Wind

Wind is moving air in the atmosphere.

Air is always moving from high pressure to low pressure.

The strongest winds are tornadoes, the air pressure is extremely low.

How to measure wind speed

Wind speed is measure in kilometres per hour (kph). We use a device called an anemometer.

Wind Direction is always stated in terms of where the wind is coming from.

Measuring Wind Direction

Wind Sock

Weathervane

Humidity- Moisture in the Air

The sun heats up the water on land and causes evaporation.

The moisture that is in the air is called humidity.

Saturated is when the air has too much moisture and cannot hold anymore.

The Water Cycle

The sun heats up the water- evaporation

The water vapor (gas) condenses into clouds

The clouds become saturated and precipitation is the result.

The precipitation pools in lakes, oceans and rivers. Waiting to evaporate again.

Relative Humidity

It is the ratio of how much moisture is in the air and how much the air can hold.

50% humidity means the air is holding 50% moisture

Precipitation

When there is too much moisture, the water will fall as precipitation.

Precipitation will fall in two main forms: rain or snow depending on the temperature of the air through which the moisture will fall.

Other forms of precipitation are sleet and hail.

Forms of Precipitation

Snow

If the air is cooled below the freezing point of water, the condensing moisture is quickly freeze into ice crystals.

The ice crystals join to make snowflakes

Snowflakes are always six sided.

Rain

When droplets of moisture join together becoming heavy enough to fall to the ground.

Hail

Formed in cumulonimbus (storm) clouds. They are frozen droplets of moisture.

Sleet

When falling rain starts off in warmer air, but passes through air below freezing, the rain drops cool and freeze onto surfaces when they hit the ground.

Facts on Precipitation

It takes 10 centimetres of snow to make one centimetre of rain.

Dew is moisture in the air cools off at night. In the morning it is found on everything. In colder temperatures, dew is frost.

Air Pressure

The force that is applied on everything on the Earth caused by the weight of the air.

Air particles are mobile, the exert pressure on objects. High air pressure brings warm, dry air. Low air pressure

brings rain or moisture Air pressure can change quickly, ie- when a storm comes

in. There are three factors that affect air pressure: altitude,

air mass temperature and the amount of moisture in the air.

A Barometer is used to measure air pressure.

Clouds

Clouds come in many shapes and forms.

Some are high in the sky, while others are so low they touch the ground.

No matter what shape or elevation, clouds form the same way, by having water vapor condense onto small solid particles like dust, sea salt, and pollution

Clouds

Clouds serve several important functions.

They provide rain and snow.

They also help retain heat, so it doesn’t escape quickly back into space.

On hot days, clouds provide shade

Can you identify these clouds?

Seasons

The Earth orbits around the sun.

The Earth tilts on its axis 23.5 degrees.

The area of the Earth, that heats up more, is closer to the sun.

Seasons

When Canada is tilted away from the sun, it is winter.

When Canada is tilted towards the sun, it is summer.

Spring and Autumn are the in between orbits.

Factors that influence weather in different areas.

Land Elevation

Location- lattitude and longitude

The sun

Cloud cover

Air pressure

Earth’s orbit (seasons)

METEOROLOGY

Known as weather science. The term comes from two Greek words meaning

‘high in the air’ and ‘knowledge’.

TEMPERATURE

Is a measure of how fast air molecules are moving.

High Pressure

Higher pressure than what is normal for that altitude.

The air becomes more dense and sinks, forming regions of high pressure.

What do you notice about the air in this region?

Brings clear skies and fair weather. The sinking cold air warms as it does so

and becomes stable.

Low Pressure

• A low pressure region (depression or cyclone) is caused by rising air.

• Clouds, rain, and very strong winds occur.

• Why do you think that is?

CLOUDS

Precipitation

Rain - Water falling in drops from vapour condensed in the atmosphere

Drizzle - Very light rain; stronger than mist but less than a shower

Dew - Water that has condensed on a cool surface overnight from

water vapour in the air

Snow - Precipitation falling from clouds in the form of ice crystals

Sleet - Partially melted snow (or a mixture of rain and snow)

Hail - Precipitate as small ice particles

Frost - Ice crystals forming a white deposit (especially on objects outside)

Cloud Types

Picture taken from:

http://commons.wikimedia.org/wiki/File:Cloud_types.jpg

Temperature & Humidity

• Temperature - Air higher in pressure is usually cooler air and air lower in pressure is usually warmer air.

• What happens when the two meet?

• Humidity - How much water is in the air over how much water could fit in the air (right before the water begins to condense out of the air).

• Dew point - Temperature at which the moisture saturates the air is the dew point.

Relative Humidity

is a measure of the amount water vapor that is present compared to the amount

that could be present at a specific temperature.

Wind

Pressure and temperature are directly related, wind can be thought of simply as air moving from one temperature or pressure to another area. The greater the difference in pressure or temperature

between two areas, the stronger the wind that blows between them will be.

SURFACE WINDS

Air that expands, becomes less dense, and gets pushed upward. Air at the equator is

heated by the rays of the Sun.

TRADE WIND (Tropical Easterlies)

Steady winds blowing from east to west above and below the equator

Westerlies and Easterlies

Prevailing Westerlies – wind blow from the west. These

winds form the boundary between cold air from the poles and

milder air closer to the equator.

Polar Easterlies – wind blow from the east. Near the poles,

cold, dense air sinks and flows away form the poles. It is

replaced by warmer air flowing in from above.

Breezes

Land Breeze – wind blowing from the land to the sea.

Sea Breeze – wind blowing from the sea to the land.

Mountain Breeze

– mountain cools rapidly than valleys. The cool heavy air on the mountainside then flows down into the valley. This is the chilly breeze you may feel in the evening.

Valley Breeze

– The air on the mountainside facing the sun therefore becomes warmer than the air over level land. With uneven heating causes a warm breeze to move up the slope.

Types of Clouds

Type Appearance Characteristics

Cirrus feathery

Fair weather clouds

Thin and curly

Consists of ice crystals because they are formed

under low temperatures at high altitudes

Cumulus

piled or heaped up/

puffy, like huge

towering columns

Heads of cauliflower with flat bottoms

Developed when rising columns of moist air are

cooled to the dew point temp.

Stratus spread out or

stretched in layers

Few hundred meters thick but may extend over

thousands of square kilometers.

Nimbus Rainy/ dark or

grayish clouds Any cloud that produces precipitation.

According to Height

Groupings according to Height in the Atmosphere Type

HIGH CLOUDS Mean lower level: 6000 m

1. Cirrus 2. Cirrostratus 3. Cirrocumulus

MIDDLE CLOUDS Mean upper level: 6000 m Mean Lower level: 2000 m

4. Altocumulus 5. Altostratus

LOW CLOUDS Mean upper level: 2000 m

Mean Lower level: close to the surface of the Earth

6. Stratocumulus 7. Stratus 8. Nimbostratus

CLOUDS OF VERTICAL DEVELOPMENT Mean upper level: that of cirrus clouds or higher

Mean Lower level: 500 m

9. Cumulus 10. Cumulonimbus