Solar energy and atmosphere

1. WHERE DOES
SOLAR ENERGY
COME FROM?

2. What is the Sun?
• The Sun is a huge sphere of gases.
• The enormous mass of the Sun is made up of almost 75% hydrogen
and 25% helium, as well as small traces of other elements.
• It is subjected to extreme conditions:
• The pressure is 250 million atmospheres (on the surface of the Earth,
the pressure is 1 atmosphere).
• The temperature reaches 16 million ºC.
• Its density is 50 times the density of water.

3. • The enormous amount of energy
emitted by the Sun is created by
NUCLEAR REACTIONS in its core.
• The source of this energy within
the Sun, are the Hydrogen atoms.
Due to the extreme pressure and
temperature inside the Sun, the
hydrogen is transformed into
helium, which in turn frees large
amounts of energy. This process is
called nuclear fusion.

4. • This energy is emitted in all directions, but only a tiny part
reaches the Earth. However, this energy is enough to enable
life to exist.
• The energy from the Sun, combined with the effects of
gravity, are responsable for the water cycle and the
geological agents that shape the landscape.

5. WHAT IS THE
ATMOSPHERE?

6. The atmosphere is a layer of gases sorrounding the planet
Earth and retained by Earth´s gravity.
Composition of the atmosphere:
It contains 78 % Nitrogen and 21% Oxygen

7. Importance of the atmosphere:
• It protects life on Earth by absorbing
ultraviolet solar radiation.
• Reducing temperature extremes
between day and night thanks to the
greenhouse effect.

8. HOW DOES SOLAR
ENERGY REACH
THE EARTH?

9. •Some parts of the Earth receive more
solar energy than others. Do you know
why is that?
Give some reasons.

10. • This phenomenon
has two reasons:
• The Earth´s axis is
tilted.
• The Earth is
spherical but it´s
not a perfect
sphere.
• This combination of
factors produce an
unequal heating of
the Earth´s Surface.

11. • As a result of this unequal heating of the Earth, air currents are created.
• Warm air from the Equator moves towards the poles.
• Cold air from the poles moves towards the Equator.
• Ocean currents function in the same way.
• This is known as the
THERMOHALINE CIRCULATION
(page 68 digital book).

12. • Now make a diagram of the Earth and mark the air and ocean
currents using arrows of two different colours to show the
direction of the warm and cold currents.