The Sun
- The role of the Sun
- Effect on Weather
- Solar Power
- Why do we have temperature
- How do we measure air temperature?

The Sun's role

The Sun is the ultimate source of heat energy of the earth. All the Earth's heat and light comes from the Sun. The heat and light reaches the Earth from the Sun in one minute is more than the amount of the whole world can produce in a year.

Life support

The Sun keeps the temperature of most of the Earth' surface at -51 to 49 degrees Celsius. Most living things can only survive at 0 to 49 degrees Celsius. If the amount of sunlight reaching the Earth was cut by one tenth, the oceans would turn to ice and life on Earth would die.

Effect on Weather

The Sun is the key to the world's weather. Its rays filter through the atmosphere and warm the Earth's surface which, in turn, heats the air above. This makes the air move because warm air rises. As the rising warm air moves farther away from the land, it cools and sinks. Air moves all over the world, causing winds which carry weather changes. Also, the Equator is hot because the Sun shines directly overhead. The Poles are cold because the rays hit the Earth at lower angles.

Did You know?
People used to think that the closer you went to the Sun, the hotter it would be. But as hot air rises it expands and cools, so the higher places on the earth you go the colder it is. Air cools by 3 degrees Celsius for every 305m it rises. This is why the tops of mountains are cold.

The Snug Earth

The Earth absorbs sunlight and then releases it into the air again as heat. The heat is trapped by water vapour and clouds in the atmosphere and reflected back to Earth. The atmosphere acts like an enormous blanket around the Earth, keeping the warmth.

Solar power

Solar panels are used to collect the Sun's heat. Water in them absorbs the heat and is used to warm homes. Electricity can also be made from sunlight. In 1982 the car The Quiet Achiever was driven right across Australia on sunshine power alone. >> Solar Panels.

Why do we have air temperature?

Temperature tells us how hot or how cold the air is. This also greatly affects the weather. It is important to us because we need to wear different clothes for different temperature; and farmers must protect their crops if temperatures are extremely high or low.

How do we measure air temperature?

Thermometers are used to measure temperature. They are placed in the shade, 1.5 m off the ground. That is because in direct sunshine and on the ground, the temperature recorded may be much higher than that off the ground. Temperature is usually measured in degrees Celsius ('C) or degrees Fahrenheit ('F). >> This photo is an example of a Six's Thermometer.

Making a simple Thermometer of your own?

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