40 Amazing Points about

The Earth, The Biosphere, The Lithosphere,

The Hydrosphere and The Atmosphere

The Earth

The Earth is the fifth largest planet in the Solar System.
2% of the total surface area of Earth is covered by continents (land), while 70.8% is covered by oceans (water).
The total water area of the including the earth including the oceans, lakes, rivers, ice sheets and the water in the atmosphere is called hydrosphere and it covers about 71% of the earth’s surface.

Biosphere

Biosphere is the biological component of earth system which includes the lithosphere, hydrosphere and atmosphere. It also includes all living organisms on earth, together with the dead organic matter.
It is a key component of earth systems, interacting with and exchanging matter and energy with the other spheres, helping to drive the global biogeochemical cycling of carbon, nitrogen phosphorus, sulfur and other elements.
Earth is the only planet in the solar system that supports life and this is because of Lithosphere, hydrosphere and atmosphere.

Lithosphere

The lithosphere is the solid rocky crust covering entire planet. This crust is inorganic and is composed of minerals. It covers the entire surface of the earth from the top of Mount Everest to the bottom of the Mariana Trench.
The Lithosphere (or land) covers two-sevenths or 29.22% of the total surface area of the earth.

Hydrosphere

The hydrosphere is composed of all of the water on or near the earth. This includes the oceans, rivers, lakes and even the moisture in the air.
Hydrosphere (or sea) covers five-sevenths or more accurately 70.78% of the total surface area of the earth.
It is used by plants for making food.

Latitude and Longitude

Any location on earth is described by two numbers- its latitude and its longitude.

Latitude

On a globe of the Earth, lines of latitude are circles of different size. The longest is the equator, whose latitude is zero, while at the poles- at latitudes 90⁰ North and 90⁰ South (or-90⁰) the circles shrink to a point.

Longitude

On the globe, lines of constant longitude (“meridians”) extend from pole to pole.
Every meridian must cross the equator. Since the equator is circle , we can divide it into 360 degrees, and the longitude of a point is then the marked value of that division where its meridian meets the equator.

Rotation of the Earth

The Earth spins (rotates) west to east on its axis once in 24 hours approximately.
The Earth’s axis is not vertical. It makes an angle of 23⁰ 30’ with the vertical or 66⁰ 30’ with the plane of the Earth’s orbit.
The Earth’s axis always points to the same direction ( Towards the pole star) as it moves around the sun. The tilt axis is known as the inclination of the Earth’s axis.

Eclipses

An Eclipse occurs when the sun, the moon and the earth are in a straight line.
A ‘solar eclipse’ occurs between sunrise and sunset on new moon when the moon passes directly in front of the sun so that its shadow lies on the earth. In other words, the moon lies between the sun and the earth.

Atmosphere

The envelope of air that completely surrounds the earth is known as atmosphere.
The atmosphere extends to about 1000 km from the surface of the earth .99% or the total mass of the atmosphere is found within the first 32km.

Composition of the Atmosphere

(i) Nitrogen-78% (ii) Oxygen-21% (iii) Argon-0.93% (iv) Carbondioxide-0.03% (v) Neon-0.0018% (vi)Helium-0.0005% (vii) Ozone-0.0006% (viii) Hydrogen-0.00005%.

Layers of the Atmosphere

Troposphere

This is the first layer of the atmosphere and contains half of it. It extends to a height of 18 km at the equator and 8 km at the poles.
It contains more than 90% of gases in the atmosphere.
Since most of the water vapours from clouds in this layer, all weather changes occur in the troposphere (“tropo” means’ change’).

Stratosphere

This is the second layer of the atmosphere. It extends from the tropopause to about 50 km.
Temperature increases due to the absorption of the ultraviolet radiation of the sun by ozone present in this layer. The temperature slowly increases to 4⁰
Hence, it provides ideal flying conditions for large jet planes.
At about 50 km the temperature begins to fall again. This marks the end of the stratosphere and is called the stratopause.

Mesosphere

Thermosphere

The thermosphere lies above the mesosphere.
This layer extends to a height of about 640 km.
It is layer with auroras.
This increase in temperature is due to the fact that the gas molecules in this layer absorb the X-rays and ultraviolet radiation of the Sun.
This results in the breakup of the gas molecules into positively and negatively charged particles or ions. Thus this layer is also known as the ionosphere.
The thermosphere also protects us from meteors and obsolete satellites, because its high temperature burns up nearly all the debris coming towards the Earth.

Exosphere

This layer lies above the thermosphere.
This is the upper limit of the atmosphere.
It has only traces of gases like oxygen, nitrogen, argon and helium. This is so because the lack of gravity allows the gas molecules to escape easily into the space.