OUR

ATMOSPHEREThe envelope of gasses that surrounds our

planet.

Atmospheric Composition

Our “air” is made up of:

-78% Nitrogen

-21% Oxygen

-0-4% Water Vapor

-0.93% Argon

-0.038% Carbon Dioxide

-0.01% Trace Gases

Carbon dioxide has increased

from 0.028% over the past 150

years. Why might this be

significant?

Our atmosphere from space

A SPECIAL COMPONENT OF OUR ATMOSPHERE -

OZONE

-Ozone molecules help to protect us from

the suns harmful UV radiation.

The ozone molecule (O3)

is created naturally in our

atmosphere when typical

oxygen molecules (O2)

gain an extra oxygen

atom.

LAYERS OF THE ATMOSPHERE:

Exosphere- the traditional boundary between Earth’s atmosphere and outer space.

Thermosphere: The layer has extremely low density which causes the temperature, temp is more than 1000°C.

This layer also contains the Aurora from solar wind!

Mesosphere: This layer actually decreases in temperature.

This is the layer that protects us from meteoroids!

Stratosphere- Here temperature increases with altitude, especially in the Ozone Layer. The UV absorption of UV radiation in the ozone causes the temperature to rise.

The OZONE layer protects humans from the extremely dangerous UV waves from the Sun.

Troposphere – The layer we live in. All weather happens here. Temps can be as low as -60°C.

Last/Outer Layer

of our

Atmosphere

Surface of EarthAtmospheric Layers

Tropopause

Stratopause

Mesopause

AIR PRESSUREAir Pressure is the weight of the air pressing

down on you.

Air Pressure and Elevation- As you go higher in elevation, the air molecules are more spread out, therefore the air is less dense. Also, there is less air above you being pulled down on you by gravity.

Air pressure and Weather:

Sunny Weather= High Pressure (approx the weight of a school bus!)

Cloudy/Rainy Weather = Low Pressure (approxthe weight of a Volkswagen beetle)

Why don’t humans crush if we are always under such extreme pressure?

Air Pressure is measured

with a barometer, in

millibars (mb)

PRESSURE-TEMPERATURE-DENSITY RELATIONSHIP

Imagine a closed container with a fixed amount of gas…..

-Air pressure and temperature: As temperature increases, so

does pressure due to the increased rate of movement of the

gas particles.

-Air pressure and density: As density increases, so does

pressure because more molecules are being crammed into a

given space.

-Temperature and density: As temperature increases,

molecules get more energized and spread out decreasing

density.

HEAT TRANSFERS-

THE WAY HEAT IS EXCHANGED ON EARTH.

Radiation: The direct transfer of heat through the air.

Examples: sunlight, heat given off from a fire or stove

Conduction: The transfer of heat from one object to another.

Example: heat from the hot pot directly to your hand, the pot directly heating the water.

Convection: The circulation of heat through a liquid or gas.

Example: warm air rising, a boiling pot of water circulating, lava lamp.

Why does warm air rise?

TEMPERATURE

INVERSIONSAn increase in temperature with height

in an atmospheric layer. Normally, an

increase in height decrease causes a

decrease in temperature.

These inversions

occur as land cools very quickly and

cold air gets

trapped under warm

air.

In highly populated

areas, this can

become a problem

because pollution

can get trapped in

the cold air near

Earth’s surface.

WIND – 2 types: local and global-All winds are caused by pressure differences between to

masses of air. The air always tends to flow from high

pressure (or density) to low pressure (or density) just like

carbonation escaping a freshly opened bottle of soda).

These pressure differences are caused by the unequal heating of

Earth’s surface.

Local wind: These are short

term winds that move over

small distances and change

from day to day or even hour

to hour. (This is what you

typically think of when you

think of wind)

Global Winds: These are long-

term movements in Earth’s

atmosphere that travel long

distances and always in the

same direction.

Think about temperature

differences (compare the

equator and the poles) and

why these winds are always

moving in the same direction.

HUMIDITY – THE AMOUNT OF WATER VAPOR IN THE

ATMOSPHERE AT A GIVEN TIME.

-Saturation: when the amount of water vapor in

the air has reached its maximum amount.

-Relative Humidity: The amount of water vapor in

a volume of air relative to the amount of water

vapor needed for that volume of air to reach its

saturation point.

For example, any saturated volume of air has

100% relative humidity.

If the air only contains half of the water vapor

needed for it to be saturated, it has a relative

humidity of 50%.

Cirrus tell that

there will be a

storm in a

couple of days

These are the

only vertical

clouds and

are the huge

thunderstorm

and tornado

clouds.Fair

sunny

weather

Rain but not

thunderstorms

Flat/Low

overcast

clouds

Dew point is the temperature at which the air can no longer hold all of its

water vapor, and that vapor begins to condense into liquid water.

CLOUD

NAMES

Shape

Height

Precipitation-Cirrus means curly or

thin.

-Stratus means layered.

-Cumulus means lumpy

or piled up.

-Cirro are clouds above

6,250 meters.

-Alto clouds are between

1,875 and 6,250 meters.

-There is no prefix for

clouds below 1,875

meters.

Clouds containing

precipitation will

have the word

Nimb somewhere

in the name.

Cloud Formation- clouds form by tiny water droplets attaching to dust particles in the sky.

Eventually the drops will build up on the dust until it becomes heavy enough for gravity to pull it to the

Earth’s surface as precipitation.

Cloud Formation Time Lapse

1. Evaporation fills the air with water vapor (gaseous water)

2. Air rises away from the surface, carrying the moisture upward.

3. As it rises, the temperature drops causing the water vapor to condense into tiny

droplets.

4. Water molecules attach to condensation nuclei (tiny dust particles that cloud

droplets form around).

5. Coalescence - The droplets continue to grow in size as condensation continues.

Most droplets will eventually collide with another droplet, increasing size.

6. Once they become heavy enough, gravity will pull them to the ground as

precipitation.

Types of PrecipitationA. Rain- liquid precipitation

B. Sleet- frozen ice pellets (less than 5mm)

C. Freezing Rain- comes down as a liquid by freezes on contact leaving a glaze of ice.

D. Snow- frozen, six-sided crystals.

E. Hail- (only forms in cumulonimbus clouds) ice pellets that circulates vertically in the clouds and forms layers as it grows bigger.

http://dsc.discovery.com/search/results.html?query=hail

Supercooling – The process by which

a substance drops below its freezing

point without turning into a solid.

The Water Cycle