One most important carecterstick of all the layer
Answers
Answer:
quora
is the correct answer
Answer :
biosphere
Explanation:
The Earth's atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other gases (1%) that surrounds Earth. High above the planet, the atmosphere becomes thinner until it gradually reaches space. It is divided into five layers. Most of the weather and clouds are found in the first layer.
From the Earth's surface extending up to between 7 and 14 kilometers is the TROPOSPHERE. This layer of the atmosphere is the densest - about 80% of the total mass of the atmosphere lies here. The troposphere is responsible for the weather on Earth. The height of the top of the troposphere varies with latitude - it is lowest over the poles and highest at the equator - and also by season it is lower in winter and higher in summer. It can be as high as 20 km near the equator, and as low as 7 km over the
poles in winter.
The STRATOSPHERE starts where the troposphere ends, and extends to 50 kilometers up. The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer. The stratosphere is very dry; the air contains little water vapor. Because of this, few clouds are found in this layer; almost all clouds occur in the lower, more humid troposphere. Jet aircraft reach their maximum operational altitudes within the stratosphere because the air is a lot thinner than at lower levels - resulting in fuel economy and less turbulence.
Above the stratosphere is the MESOSPHERE which extends from 50 km to about 80 km up. Temperature decreases with height throughout the mesosphere. The coldest temperatures in Earth's atmosphere, about -90° C is found near the top of this layer. Not much is known about the mesosphere because weather balloons and other aircraft cannot fly high enough to reach the mesosphere; satellites orbit above the mesosphere and cannot directly obtain data on this layer.
The next layer is the THERMOSPHERE which extends right up to 600 kilometers. Auroras occur in this layer. Temperatures rise sharply in the lower thermosphere - below 200 to 300 km altitude - then level off and hold fairly steady with increasing altitude above that height. Solar activity strongly influences temperature in the thermosphere. The thermosphere is typically about 200° C hotter in the daytime than at night, and this can increase to 500° C when the Sun is very active. (Active Sun means more sunspots and solar flares) Temperatures in the upper thermosphere can range from about 500° C to 2,000° C or higher.
Although the thermosphere is considered part of Earth's atmosphere, the air density is so low in this layer that most of the thermosphere is what we normally consider as 'outer space'. In fact, the most common definition says that 'space' begins at an altitude of 100 km. The International Space Station and several satellites orbit the Earth within the thermosphere.
Much of the X-ray and UV radiation from the Sun is absorbed in the thermosphere. When the Sun is very active and emitting more high energy radiation, the thermosphere gets hotter and expands or "bloats". Because of this, the height of the top of the thermosphere varies. Since many satellites orbit within the thermosphere, changes in the density of air at orbital altitudes brought on by heating and expansion of the thermosphere generates a 'drag' and satellites occasionally need to be boosted higher to offset the effects of the drag force.
The upper limit of our atmosphere is the EXOSPHERE It extends from the top of the thermosphere and fades away into space. Actually, since the exosphere gradually fades into outer space, there is no clear upper boundary of this layer. One definition of the outermost limit of the exosphere places the uppermost edge of Earth's atmosphere around 190,000 km, about halfway to the Moon.
The IONOSPHERE is a layer of electrons and ionized atoms and molecules that stretches from about 50 kilometers above the surface of the Earth up to the edge of space at about 1,000 km, overlapping into the mesosphere and thermosphere. High-energy solar photons tear electrons away from gas particles in the thermosphere, creating electrically-charged ions of atoms and molecules. Earth's ionosphere, composed of several regions of such ionized particles in the atmosphere, overlaps with and shares the same space with the electrically neutral thermosphere. This dynamic region grows and shrinks based on solar conditions. This region is what makes radio communications possible.