Rotation and revolution


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Rotation and revolution

  1. 1. The Earth is a watery planet because oceans cover over 72 % of its surface. It is made up of rocks, water and air. It has life on it. The earth is moving all the time
  2. 2. The EQUATOR is an imaginary line that divides the earth into two equal halves. It goes right around the earth like a belt that is tied around your waist. It divides the earth into Northern Hemisphere & Southern Hemisphere. The top- most tip of the earth is the North Pole. Directly opposite is the southern-most tip called South Pole. The Axis is an imaginary line that connects the north pole & the south pole & the centre of the Earth. North Pole South Pole EQUATOR
  3. 3. ROTATION Like the other planets, the Earth spins like a top on its axis. We call this movement Rotation. Rotation is the daily movement of the earth on its axis from West to East. It takes 24 hours to complete one rotation. This equals one day and one night. Rotation of the earth causes day and night.
  4. 4. Rotation of the Earth causes day and night. The side of the Earth that faces the sun has day. The opposite side has night. Rotation always takes place from west to east.
  5. 5. REVOLUTION The Earth also moves around the sun in a set path called the orbit. The movement of the Earth around the sun is called Revolution. It takes 365 days & 6 hours to complete one revolution. This equals one year. The revolution of the Earth causes seasons.
  6. 6. The revolution of the Earth around the sun causes seasons. We have different seasons in a year-summer, rainy, winter, autumn and spring. The axis of Earth is tilted a little. As the Earth revolves, the pole and the hemisphere of the Earth that is tilted towards the sun is warmer and has summer. The pole and the hemisphere which is tilted away from the sun this time has winter as it gets less heat.
  7. 7. Different places on the Earth get different amounts of heat. This causes changes in the condition of the air from time to time and place to place. The condition of the air at a given time and place with respect to hotness or coldness, wind, rain, sunshine, etc. is known as WEATHER.
  8. 8. Climate is the average picture of weather conditions in a place over a long period of time. Meteorologist study the weather conditions of a place and the seasons it has for at least thirty years before deciding what the climate of the place is. The temperature of the air and the wind pattern are two important factors that causes the change in seasons and climate of a place.
  9. 9. Sea breezes are winds that are caused by the differential heating rates of land and sea. During the day the land heats up more rapidly than the sea because: •land has a lower specific heat than water - it requires less heat to raise the temperature of 1 kilogram of earth by 1 degree than it does for water; •the incoming heat warms a shallower layer of the land because earth is a poor conductor of heat. In water the heat is spread through a significant depth by conduction, convection and forced mixing. Warm air over the land rises creating a lower pressure at the surface and a higher pressure at the altitude that the air is lifted to. Cool air from over the sea which is now at a higher pressure tends to move in to the low pressure area over land. A circulation is established as the air over the sea subsides and warm air from over land moves in to take its place.
  10. 10. During the day the land gets heated up faster than the sea. Thus the cool air from the sea blows from the sea towards the land causing sea breeze.
  11. 11. During the night the land gets cooler up faster than the sea. Thus the cool air from the land blows from the land towards the sea causing land breeze.