BREATH IT IN!!The Earths Atmosphere

What will happen in the future if we don’t change?AOI: Environments

Contents Composition of the earths atmosphere

and it’s properties Structure of the atmosphere Atmospheric Pressure The importance of the atmosphere Observing the sky Atmospheric phenomena Air pollution

Composition of the atmosphere

The atmosphere is a gaseous layer which surrounds the planet

It is about 500 km thick, but most of the gases are in the troposphere (0 km to 15 km up)

Air is mainly made of Nitrogen (78%), Oxygen (21%), Carbon dioxide (0.04%), Water vapour ( around 1%) and other gases like argon (around 1 %)

Composition of the atmosphere

These gases are a mixture because they are not chemically bound together and can be seperated.

For more on gases:http://www.skoool.ie/skoool/junior.asp?id=400

Structure of the atmosphere

Atmospheric layersTroposphere This is

where all plants and animals live and breathe

Where weather takes place

Air is mixes T decreases

with altitude

Atmospheric layersStratosphere Ozone in this layer

stops many of the sun's harmful rays from reaching the earth

People can not breathe in this layer.

Atmospheric layersMesosphere T decreases

with altitude This is where

we see “shooting stars" – meteors burning up as they fall to Earth

Atmospheric layersThermosphere 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.

Nitrogen and Oxygen

· the two most common gases; found throughout all the layers

Ozone · a form of oxygen found in the stratosphere

Water vapor andCarbon dioxide

· important gases for weather conditions; found in thetroposphere

Trace gases, argon

· play an insignificant role

AIR PRESSURE

Keeping an Atmosphere Atmosphere is kept by the world’s gravity

Low mass (small) worlds= low gravity =almost no atm. High mass (large) worlds = high gravity = thick atm.

Gravity and pressure Air pressure depends on how much gas there

is i.e. The atmospheric thickness.

Gravity and Atmospheric Pressure The stronger the gravity, the more gas is held by the world

and the greater the weight of atm. on a point

The air is made up of molecules.

Gravity pulls the air molecules toward the earth, giving them weight. The weight of the air molecules all around us is called the air pressure.

High altitudes = lower pressure

Low altitudes = higher pressure

Atmospheric Pressure

Gas pressure depends on both density and temperature.

Adding air molecules increases the pressure in a balloon.

Heating the air also increases the pressure.

Air pressure is equal in all directions.

Pressure = force per unit area

As elevation goes up

Barometric pressure

goes down.

This is an inverse relationship.

In 1643, Evangelista Torricelli invented the barometer

Torricelli’s barometer used a glass column suspended in a bowl of mercury. The pressure of the air molecules pushed the mercury up into the glass tube.

The weight of the mercury in the tube was equal to the weight of the air pressing down on the mercury in the dish.

As atmospheric pressure increases…

The mercury in the tube rises.

The Mercury Barometer

Good: Bad:

•Simple to construct

•Highly accurate

•Glass tube is fragile

•Mercury is very toxic!

The Greenhouse effect http://

www.skoool.ie/content/skoool_learning/junior/lessons/science/conservation/flash/h-frame-ns6.htm

Pages 1-10

The Greenhouse effect

The Greenhouse Effect is NOT the same as Global Warming

The Greenhouse Effect Light contains energy and travels like a

wave

The Greenhouse Effect Too much light energy is staying in the

atmosphere because of greenhouse gases like Carbon Dioxide and Methane

This is making the planet hotter overall This is causeing problems like:1. Flooding (ice caps melting)2. Drought3. Destrcuction of habitats and ecosystems