Question

what is atmosphere? How many layers are there​

Answer 1

Answer:

The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere

Answer 2

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Atmosphere is a protective layer of gases that shelters all life on Earth, keeping temperatures within a relatively small range and blocking out harmful rays of sunlight.”

An atmosphere is a blanket of gases that surrounds Earth. It is held near the surface of the planet by Earth’s gravitational attraction. Argon, oxygen and nitrogen from the three main constitutions of the atmosphere.

The atmosphere:

contains the air that we breathe

helps retain the sun’s heat and prevents it from escaping back into space

protects life from harmful radiation from the sun

plays a major role in Earth’s water cycle

helps keep the climate on Earth moderate

There is no boundary between the atmosphere and outer space. The atmosphere gets less dense and denser until it “blends” into outer space.

Layers of Atmosphere

What do you see when you stand outside and lookup? A blue sky? A group of clouds? At night you might see a crescent moon, stars, a satellite. What you are not seeing, however, is the complexity of our atmosphere.

The atmosphere has five distinct layers that are determined by the changes in temperature that happen with increasing altitude. Layers of Earth’s atmosphere are divided into five different layers as:

• Exosphere
• Thermosphere
• Mesosphere
• Stratosphere
• Troposphere.

Troposphere

The troposphere is the lowest layer in the atmosphere. It extends upward to about 10kms above sea level starting from ground level. The lowest part of the troposphere is called the boundary layer and the topmost layer is called the tropopause. The troposphere contains 75% of all air in the atmosphere. Most clouds appear in this layer because 99% of the water vapour in the atmosphere is found here. Temperature and air pressure drop as you go higher in the troposphere. When a parcel of air moves upwards it expands. When air expands it cools. Due to this reason, the base of the troposphere is warmer than its base because the air in the surface of the Earth absorbs the sun’s energy, gets heated up and moves upward as a result of which it cools down.

Stratosphere

Above the troposphere lies the stratosphere which extends from the top of the troposphere to about 50 km (31 miles) above the ground. The ozone layer lies within the stratosphere. Ozone molecules in this layer absorb high-energy ultraviolet (UV) light from the Sun and convert it into heat. Because of this, unlike the troposphere, the stratosphere gets warmer the higher you go!

Mesosphere

Above the stratosphere is the mesosphere and it extends to a height of about 85 km (53 miles) from the ground. Here, the temperature grows colder as you rise up through the mesosphere. The coldest parts of our atmosphere are located in this layer and can reach –90°C.

Thermosphere

Thermosphere lies above the mesosphere and this is a region where the temperature increases as you go higher up. The temperature increase is caused due to the absorption of energetic ultraviolet and X-Ray radiation from the sun. However, the air in this layer is so thin that it would feel freezing cold to us! Satellites orbit Earth within the thermosphere. Temperatures in the upper thermosphere can range from about 500° C to 2,000° C or higher. The aurora, the Northern Lights and Southern Lights, occur in the thermosphere.

Exosphere

Exosphere is the final frontier of the Earth’s gaseous envelope. The air in the exosphere is constantly but gradually leaking out of the Earth’s atmosphere into outer space. There is no clear cut upper boundary where the exosphere finally fades away into space.

Ionosphere

The ionosphere isn’t a distinct layer unlike other layers in the atmosphere. The ionosphere is a series of regions in parts of the mesosphere and thermosphere where high-energy radiation from the Sun has knocked electrons loose from their parent atoms and molecules.

Hope it helps you :)