What is atmosphere??
jaydip1118
Answers
Explanation:
The atmosphere is the blanket of gases which surrounds Earth. It is held near the surface of the planet by Earth's gravitational attraction.
Without the atmosphere there could be no life on Earth. The atmosphere:
contains the air we breathe;
protects life from harmful radiation from the Sun;
helps keep the planet's heat from the Sun from escaping back into space;
is a major element of the water cycle;
keeps the climate on Earth moderate compared to that of other planets.
The atmosphere is made up of a mixture of gases, mostly nitrogen, oxygen, argon and carbon dioxide. It reaches over 500km above the surface of the planet. There is no exact boundary between the atmosphere and outer space. Atmospheric gases become thinner the higher up you go. The atmosphere just keeps getting less and less dense, until it "blends" into outer space.
The atmosphere is divided into four layers based on temperature: the troposphere, stratosphere, mesosphere, and thermosphere.
The Troposphere
This is the lowest layer of the atmosphere, closest to the surface of the earth. The troposphere varies in height in different parts of the world, from about 8km above sea level at the poles, to 16km at the equator. Within the troposphere, the temperature drops rapidly the higher you go.
This is the layer where we see clouds and most of the "weather" occurs.
The top layer of the troposphere is called the tropopause. Within the troposphere the temperature drops to a low of -56ºC. This marks the beginning of the tropopause. Through the tropopause, the temperature reverses and begins to increase. The height of the tropopause varies from the poles to the equator, but also from the summer to winter.
The Stratosphere
For a distance of about 18km above the tropopause, there is a layer called the stratosphere. In this layer, the pressure continues to decrease, but the temperature increases gradually to 0ºC.
Like the troposphere, the stratosphere also varies in thickness. It is quite deep over the poles and thinner over the equator.
The stratosphere contains a layer of ozone which absorbs the Sun's ultraviolet rays, protecting life on the earth's surface.
The top layer of the stratosphere is called the stratopause. In this layer the temperature, once again, begins to fall.
The Mesosphere
The mesosphere reaches up to about 80km above the surface of the earth. This is the coldest layer of the atmosphere, where the temperature drops rapidly with altitude.
In the top layer of the mesosphere, called the mesopause, the temperature bottoms out at a low of about -100ºC at 80km above the earth. After that the temperature begins to rise again with greater altitude.
This is the layer where meteorites usually burn up as they enter the atmosphere.
The Thermosphere
The thermosphere extends upwards from a point 80-100 kilometres above the earth's surface. There is very little air in this layer. The temperature continues to rise in the thermosphere and beyond, increasing for an indefinite distance into space.
The Exosphere
The exosphere is the very outer limit of the atmosphere. The bottom of this layer is found at 500 kilometres above the Earth's surface. The pressure drops to little more than a vacuum. Auroras form in the exosphere.
Answer:
Atmosphere is a thick layer of air surrounding earth
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