AtmosphereTwitter: @LilyKotze

Our Atmosphereis a layer of gases which surrounds the earth.

These gases are held in place by the earth’s gravitational force.

This mixture of gases consist mainly of Nitrogen (78 %), Oxygen (20 %), Inert gases – mainly Argon (0,93 %) and Carbon dioxide and other gases (0,03 %). Water vapour makes up the last 1 %, but is only present in the lower atmosphere, where weather phenomena occurs.

Nitrogen Gas78%

Oxygen Gas20%

Carbon Dioxide and other gases0,03%

Inert gases (mainly Argon)0.97%

Water vapour1%

most denseThe atmosphere is

close to earth.

The density decreases as the height above sea-level increases, until in outer space where the density is zero.This means there is no air in outer space.

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hSource of O2 - supports life

Nitrogen is unreactive, and

dilutes the oxygen.

Nitrogen is fixed in the air by lightning and bacteria in the ground and is then absorbed by plant roots for maximum

plant growth.

CO2 is needed for

photosynthesis.

Protection from UV rays. (See Ozone layer)

Temperature fluctuation between day and night are less severe, otherwise we would be KFC in the daytime and icicles at night.

The atmosphere is divided into

four layers (some say five).

This division is based upon temperature differences.

Each layer has a transition point. These transition points are known as a pause.

Sometimes the top part of the thermosphere is referred to as the exosphere.

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Closest to the earth (6km – 20 km):Responsible for maintaining life and weather systems . (Contains all the water vapour present in the atmosphere.)

Is the most dense – contains 70 % of the mass of the atmosphere.

Temperature decreases with height. This is called a positive lapse rate.

Tropopause is the upper layer of the troposphere and transitions into the

stratosphere.

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Contains 24 % of the atmospheric mass – the atmosphere here is very thin. (20 – 50 km)

Contains the ozone layer (O3): Ozone converts harmful UV rays from the sun into heat. This causes and increase in temperature as the

height increases, which is called a temperature inversion.

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50 – 85 km

Coldest part of the atmosphere – known as the mesopheric temperature minimum. The temperature decreases as the height increases.

Protective function: these is still enough air so small rocks and substances from space are incinerated – this is usually known as

‘shooting stars’.

Temperature increases with height (85 – 690 km)

Extremely high temperatures due to the absorption of energetic UV- and X-rays at the bottom of the thermosphere.

Air is VERY thin.

Radio and T.V. transmissions reflected to the earth here.

Ionosphere is part of the Thermosphere. This is

where charged particles interact with the

magnetosphere to for the Northern (or Southern)

Lights.

ISS orbits at approximately 370 km

This is the top layer, where the atmosphere is extremely thin and blends with space.

Each layer has a different temperature gradient.

Definition

is the changein temperaturewith height above sea level.

Title slide: http://www.mediafactory.org.au/matthew-jowett/files/2014/08/atmosphere-tn5co9.jpg Slide 5: http://hendrix2.uoregon.edu/~imamura/102/images/Sea-Level-Barometric-Pressure.jpg Slide 8 – 12: http://www.teara.govt.nz/files/di-6132-enz.jpg Slide 15: http://www.weatheronline.co.uk/reports/wxfacts/atmo200.jpg DocScientia Grade 9 Natural Sciences CAPS. Textbook and workbook. Third edition 2013