The Earth's revolution

4. THE EARH’S REVOLUTION -

The Earth rotates around the Sun in an elliptical movement called revolution.

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It takes the Earth 365 days and 6 hours to complete a full revolution.

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Each four years, we add an extra day to the month of February to adjust the extra six hours.

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A year of 366 days is called leap year.

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The Earh’s revolution and tilted axis have 2 consequences: 1. seasons 2. Lenght of day and night

4. THE EARH’S REVOLUTION 

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1. SEASONS : - spring, summer, autumn and winter.

- They are produced because of the different inclination of the Sun’s rays when these reach the Earth.

2. LENGHT OF DAY AND NIGHT: - Due to the tiltted axis, each hemisphere is illuminated differently.

 At the Equinoxes : - Sun’srays are vertical at the Equator - spring equinox (21st March) - autumn equinox ( 23rd çseptember) - Both hemispheres receive the same amont of solar energy - Day and night have the same lenght.

At the solstices: - Sun’s rays are vertical at the tropics.

- At the summer solstice (21st June) in the Northern Hemisphere, sun’s rays are vertical at the Tropic of Cancer (23º 27 ‘ N) - At the winter solstice (21t December) in the Northern Hemisphere, sun’s rays are vertical at the Tropic of Capricorn (23 27’ S)

4. THE EARH’S REVOLUTION • CLIMATE ZONES - The tilt of axis influences the world’s climate zones - Different parts of the Earth receive varying amount of solar energy.

- Sun’s rays reach reach intertropical regions at a direct angle for all most of the year.

- Sun’s rays reach the poles at a small angle.

- - There are 3 climatic zones : Tropical, 2 temperate, 2 polar regions.

4. THE EARH’S REVOLUTION 

The TROPICS:

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TWO TEMPERATE ZONES: - located between the tropics and the polar circles, in each hemispheres - Number of daylight hours falls between summer and winter solstices.

- Four seasons.

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TWO POLAR REGIONS: - located between the polar circles and the poles.

- Temperatures are always very low - Big differences beween the length of day and night - Sun is visible for six months at each pole, in summer.

- Despite of being summer Sun provides little heat because rays reach the Earth at a low angle.

- Are located between the Tropic of Cancer and the Tropic of Caricorn.

- They receive the greates amount of solar energy.

- Temperatures are high all the year - There are little difference between seasons

THE EARTH’S REVOLUTION AND THE SEASONS

CLIMATE ZONES