Block 5 – Lesson 2

Do you think the Sun is a

natural source of heat and

light?

Most of the Earth’s energy comes from the Sun. It is

important because it provides light and heat. Without the

Sun’s heat and light, there would be no life on Earth, and

the oceans would freeze.

Our planet without the Sun

Most radiations from the Sun is absorbed by the

atmosphere. The types of radiation that reach the

Earth’s surface are visible light (white), ultraviolet light,

and infrared light.

Solar light is energy. It heats the Earth and it is the

force behind climate and atmospheric weather.

When the Earth receives light from space, part of it

is absorbed and the rest bounces back to the

atmosphere through reflection.

Reflection is the bouncing of the light when it hits a

body, like the Earth and clouds. The Sun’s light also

experiences a change of direction when passing

from one material to another, for example from air to

water, or from hot to cold air.

In this case, the rays of the Sun are refracted.

A rainbow is formed in this way.

Heat is another form of energy. It can pass from one

body to another. Temperature is measured with a

thermometer.

When the Earth’s surface is heated, it receives the

heat radiation. In ecosystems, one part of this

energy is used to evaporate water and the rest

returns to the atmosphere.

Climate factors are: temperature, wind, humidity,

precipitation and pressure. The relationship between

these five factors and the Sun’s radiations, altitude

and latitude determines the types of climate.

The types of climate

determine the

characteristics of the

fauna and flora in

ecosystems.

… is how you see yourself!