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Atmosphere Atmosphere – layer of gases that protect Earth.

The Atmosphere is Called ‘Thin Blue Line’ Picture from International Space Station

Our fragile biosphere's only protection from the solar wind's full onslaught is provided by the Earth's atmosphere (the thin blue layer in the photograph) and its magnetic field (which acts as a shield against the sun's radiation and magnetic fields).

Atmophere composition:78% Nitrogen, 21% Oxygen, 1% H 2 O, CO 2 and others

MIR SPACECRAFT

Layers of the Atmosphere: 1. Troposphere – we live here!

Weather happens here. Air pressure decreases with altitude increase. At the top it is 10% of sea level pressure. Temperature decreases with altitude(not in all layers) Boundary with the next layer is called the tropopause.

2. Stratosphere

Jet stream – bands of high-speed winds in upper tropo. and lower strato. Ozone exists in this layer. – Absorbing the UV from the sun. – Causes this layer to heat up as altitude increases. Boundary is called the stratopause.

3. Mesosphere

Coldest layer - but this is where meteors burn up. Boundary called the mesopause.

4. Thermosphere – 2 parts UPPER LIMITS EXTENDS INTO THE VACUUM OF SPACE

A. Ionosphere

Temperature increases steadily here. Area ionized by solar radiation. – Solar radiation absorbed by gases cause the atoms of the gases to lose electrons and produce ions and free electrons. This causes auroras to happen.

Alaska Auroras that occur in the northern hemisphere are called ‘Aurora Borealis’ or ‘northern lights’ and auroras that occur in the southern hempishere are called ‘Aurora Australis’ or ‘southern lights’.

Both Aurora’s can be seen in the northern or southern hemisphere, in an irregularly shaped oval centered over each magnetic pole. Scientists have learned that in most instances northern and southern auroras are mirror-like images that occur at the same time, with similar shapes and colors. Auroral displays can appear in many vivid colors, although green is the most common. Colors such as red, yellow, green, blue and violet are also seen occasionally. The auroras can appear in many forms, from small patches of light that appear out of nowhere to streamers, arcs, rippling curtains or shooting rays that light up the sky with an incredible glow.

B. Exosphere

Region where atoms and molecules escape into space. Satellites orbit here. The Jason-2 satellite orbits Earth. It carries tools and sensors to help scientists study the oceans. Image Credit: NASA

Construct layers of the atmosphere