Earth

The earth is the third planet from the sun. It is the only known planet in the solarsystem with life on it because it has all the favorable condition for the existence of life. Reflected light from the earth when seen from the space is seen as blue or bluish-green hence it is named as Blue Planet.

The temperature on the earth on an average varies from 15oC to 55oC making it most suitable for life to exist. It is enveloped in an atmosphere of gases, which includes mainly oxygen, carbon dioxide, and nitrogen it has own natural satellite called Moon. The atmosphere of this planet extends up to 800km.

layers of atmosphere
text-layout-design Atmosphere

The earth atmosphere is divided into layers according to major changes in temperature, the five concentric layers are: Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.

design-1
Troposphere

The troposphere is the lowest region in the earth’s atmosphere. On the earth it goes from ground or water level up to about 11 miles high. The weather and clouds occur in the troposphere. In the troposphere, the temperature generally decreases as attitude increases. The troposphere contains 75% of the gases in the atmosphere. This is where you live and where weather occurs.

Stratospher

The stratosphere is characterized by a slight temperature increase with attitude and the absence of clouds. The stratosphere extends between 11 and 31 miles above the earth’s surface. This layer absorbs a lot of UV solar energy. Only the highest clouds are in the lower stratosphere . Ozone acts as a shield for the earth’s surface. It absorbs UV radiation from the sun. This causes a temperature increase in the upper part of the layer.

Mesosphere

The mesosphere is characterized by temperature that quickly decreases as height increases. The mesosphere extends from between 31 and 50 miles above the earth’s surface. The temperature drops in this layer to about 100oC. This is the coldest region of the atmosphere. This layer protects the earth from meteoroids. They burn up in this area.

Thermosphere

In the thermosphere, temperature increases with attitude. The thermosphere means ‘heat sphere’. The temperature is very high in this layer because UV radiation is turned into heat. Temperature often reaches 2000oC or more.

Exosphere

The exosphere is the outermost layer of the earth’s atmosphere. The exosphere goes from about 400 miles high to about 800 miles. The lower boundary of the exosphere is called the critical level of escape, where atmospheric pressure is very low and the temperature is very low. The air is very thin here. This is the area where satellites orbit the earth.

background

Function of the Atmosphere

  1. Protection of all life from hazardous or deadly radiation from space.

  2. Protection from rapid cooling at night and heating at day.

  3. Storage of huge amount of nitrogen.

  4. Reservoir for carbon dioxide and oxygen.

  5. Protection from smaller meteorites that burn up by heating from the friction when entering the earth’s atmosphere and cannot reach the surface.

  6. Letting pass the vitally important sunlight to the surface of the continents and oceans.

atmosphere
layers of earth

layers of the Earth


Interior of the Earth. The crust, the mantle, and the core are the three layers that make up the earth. The core only forms 15% of the earth’s volume, whereas the mantle occupies 84%. The remaining 1% is made up of the crust.

layers
design-2
Crust

The outermost layer (where we live) of the earth is called the crust. It is coldest layer of the earth. It consists of rocks like granite, basalt etc. The thickness is around 0-60km.

Mantle

Mantle is the widest section of the earth. Its thickness is approximately 2,900 km. The mantle is mainly made up of semi-molten rock known as magma. The rock is hard in upper part of the mantle but lower down the rock is softer and begins to melt. Its temperature varies between 1600oF at the upper part to 4000oF near the bottom.

Core

The innermost layer of the earth is called core. It is the center of the earth. It is the hottest part of the earth. It is further divided into an Inner core and Outer core.

Outer core: - The outer core of earth is similar to a very hot ball of metals, whose temperature is around 4000oF to 9000oF. It is so hot that the metals inside are all liquid. The outer core is around 1800 miles under the crust and is approximately 1400 miles thick. It is composed of metals such as iron and nickel. The outer core surrounds the inner core.

Inner core: - It is the center and the hottest layer of the earth. The inner core is solid and made up of iron and nickel with temperature up to 5,500oC. Due to its immense heat energy, the inner core is more like the engine room of the earth. The inner core has pressures and temperatures so high that the metals are squeezed together and not able to move like a liquid but are forced to vibrate instead of solid.