The Planet's Atmospheric Layers

Our Solar System consists of the sun (Sol) and the eight planets of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

The Earth, which is also known as the Blue Planet due to it's vast amount of water, is the third planet from the sun after Mercury and Venus and is positioned some 150,000,000 kilometers away from the sun.

Earth is the solar system's fifth largest planet and the largest of the solar system's four terrestrial planets, the others being Mercury, Venus and Mars.

Earth is protected by six atmospheric layers. Without these protective screens there would be no atmosphere to absorb or reflect back the sun's harmful rays. The planet would be an arid desert baked by radiation by day and frozen by night.

Fifteen per cent of incoming radiation is absorbed by the atmosphere, and a further 35 % is reflected back into space by clouds and the surface of the land and sea. The remaining 50 % is absorbed at sea and ground level.

Our atmosphere here on earth is an envelope of gases, 99 % nitrogen and oxygen, these gases in which all life on earth depends, are secured to the surface of the earth by the planet's own gravity.

Above us as well as our own atmospheric layer are five more layers which shield us from the sun's rays and the freezing temperatures of outer space. These layers are described below.

THE TROPOSPHERE.

Found fifteen kilometers above the earth's surface, most of the atmosphere's water vapour and dust hovers here as well as the earth's weather and cloud formation.

There are three types of cloud cover - low, medium and high. Found between one thousand and five thousand feet above the ground are the four types of low cloud cover - the stratus, stratocumulus, cumulus and cumulonimbus clouds. Found between five thousand and twenty thousand feet above the ground are the three types of medium cloud cover - the nimbostratus, altostratus and altocumulus clouds and found between twenty and forty thousand feet above the ground are the three types of high cloud cover - cirrus, cirrustratos and cirruscumulus clouds.

THE STRATOSPHERE

Found between fifteen and fifty kilometers above the earth's surface, most of the earth's ozone is concentrated here, where it forms a protective layer that absorbs ultra-violet radiation. It is also here where the rare and beautiful nacreous clouds, found between 68,000 and 100,000 thousand feet over the two Polar regions, are formed.

THE MESOSPHERE

Found between fifty and eighty five kilometers above the earth's surface, it is here that temperatures fall with increasing height. It is here where rare noctilucent clouds are formed, seen as luminous clouds over polar regions at around 200,000 thousand feet high during the Summer months. It is also in this layer that the vast majority of space junk or space debris can be found orbiting the Earth.

THE THERMOSPHERE OR IONISPHERE

Found between eighty five and four hundred and fifty kilometers above the earth's surface, where the upper atmosphere begins. Gas molecules are sparse and air is extremely thin with no clouds or water vapour. Temperatures begin to rise again with height as atoms become electrically charged by solar radiation.

It is in this layer that the International Space Station (ISS) orbits the Earth at a speed of 17,500 mph (27,600 km/ph) between 330 and 410 kilometers above us.

It is also here where the two terrestrial auroras over the polar regions can be found. These auroras, which are formed when the magnetosphere (see below) is disturbed by solar winds known as geomagnetic storms, are better known as the Northern Lights (Aurora Borealis) and the Southern Lights (Aurora Australis).

THE EXOSPHERE

Found between four hundred and fifty and nine hundred kilometers above the earth's surface and lying at the edge of space, this layer has no gases, but particles from the earth's gravity pass through it before vanishing into space. It is in this area that weather and communication satellites are positioned.

THE MAGNETOSPHERE

Found nine hundred kilometers above our surface, where most of the charged particles emitted by the Sun are deflected. It is an airless protective shield created by the earth's magnetic field. It is in this layer that the two radiation belts known as the Van Allen Belts exist. These two belts of charged particles, also known as plasma which are formed by solar wind particles and cosmic rays, consist of an inner belt of electrons and an outer belt of protons held in place by the earth's magnetic field.

Check out the Earth's dimensions on our page - The Worlds Dimensions and Extremes

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