What is the atmosphere? know more.

Our atmosphere most probably evolved from gases spewed out from early volcanos at the formation stages of the earth’s surface. Oxygen is added further most likely by the process of photosynthesis for years together.

What is the atmosphere?

Our atmosphere most probably evolved from gases spewed out from early volcanos at the formation stages of the earth’s surface. Oxygen is added further most likely by the process of photosynthesis for years together. The atmosphere extends from Earth’s surface approximately 400 miles where it touches space.

It has a five layers structure of different characters, compositions, densities, and temperatures, etc. The layers from lowest to highest are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

Layers of Atmosphere

Troposphere:

The troposphere is the lowest layer of the earth’s atmosphere. Starting from the ground level it extends up to on average 14.5km(9 miles) in height, with its height lower at Earth’s poles and higher at the equator.

The troposphere accounts for the majority of the atmosphere’s mass of about eighty percent and ninety-nine percent of all the water vapour and aerosols (minute solid or liquid particles suspended in the atmosphere). Most of the weather happens here and almost all the clouds form here (with the exception of cumulonimbus thunderclouds).

The rain, tornadoes, cloud blasts, hurricanes, cyclones, and the seasons all happen in this layer. At sea level, air pressure measures 1000 mill bars. It decreases by approximately half with every four miles of altitude. The average surface temperature comes to 59 degrees F. The “Higher you go cooler you feel” principle applies here. Most aviation (commercial ) activities happen here.

Stratosphere:

The next layer above the troposphere is called the stratosphere. An atmospheric boundary tropopause separates the troposphere from the stratosphere. The stratosphere extends from the top of the troposphere to approximately 50km(31 miles)above ground.

Strong and steady winds flow here. The ozone layer is found in this stratosphere. This layer is very important for the existence of lives on the earth as Ozone molecules in this layer absorb Ultra Violate(UV) light from the Sun, and convert it into heat. The “Higher you go warmer you feel” principle applies to the stratosphere. Most jets/ supersonic fighters fly in this region.

Mesosphere:

Above the stratosphere, the mesosphere layer is presently being separated from the stratosphere by stratopause. It extends up to the height of 85km(53 miles) above the earth’s surface.

Meteors burn up in the mesosphere. Like the troposphere “higher you go cooler you feel” principles apply to this layer. The coldest temperature in earth’s atmosphere about -90 degree C (-194 degree F) are experienced near the top of the mesosphere. The air in this layer is very thin, and not fit for breathing.

Thermosphere:

The layer above the mesosphere is called the thermosphere. Mesopause separates the mesosphere from the thermosphere. The thermosphere extends up to 600km (373 miles) of the earth’s surface.

It absorbs High energy X-Ray and UV radiations coming from the Sun, raising its temperature to hundreds or at times thousands of degrees. The temperature in the upper thermosphere can range between 500 degrees C (932 degrees F) or more. However as the air in this layer is so thin, it would feel very very cold to be humans.

Many satellites orbit earth within the thermosphere. The aurora ( a natural electrical phenomenon characterized by the appearance of streams of reddish or greenish light in the sky, especially near the northern or southern magnetic pole) happens here.

In northern and southern regions it is respectively called aurora borealis or the northern lights and aurora australis or southern lights. Inter National Space Station (408 & 410 km)( 254 & 255 miles), and Tiangong Space Station (340 & 450 km) (211 & 280 miles) orbit the earth in this layer.

Exosphere:

The exosphere is the outermost layer of Earth’s atmosphere and extends from the exobase ( the lower boundary of the exosphere). This layer separates the rest of the atmosphere from outer space and is about 10,000 km (6,213 miles) wide. The outermost limit of the exosphere is around 190,000km (118,060 miles) of the earth’s surface.

The exosphere is mostly composed of extremely low densities of hydrogen, helium, and several heavier molecules including nitrogen, oxygen, and carbon dioxide close to the exobase. Most of the satellites orbit the earth in this layer. No air to breathe in this sphere and is very cold to feel.

Ionosphere:

The ionosphere is an active part of the atmosphere and it grows and sinks depending on the energy it absorbs from the Sun. As the gases in these layers are converted into ions by solar radiation, which is called the ionosphere. It overlaps the mesosphere, thermosphere, and exosphere. Parts of the ionosphere overlap with the earth’s magnetosphere.

Conclusion:

Our earth has a five layers structure atmosphere of different characters, compositions, densities, and temperatures, etc. The layers from lowest to highest are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Every sphere has specific characteristics.

Many scientists are reluctant to include the exosphere in the atmosphere but in space. As discussed different layers of the atmosphere are approximate figures, still many things left for exploration.