Module 17

• When the sun rays strike the Earth's surface near the equator, the incoming solar radiation is more direct. ( Nearly perpendicular or close to a 90 degree angle

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• The solar radiation is concentrated over a small surface area, causing warmer temperature.
• At hinger latitudes, the angle of solar radiation is smaller than 90 degree causing energy to be spread over a large area of the surface , causing cooler temperature.
• Because the angle of radiation varies depending on the latitudes, surface on average are warmer at lower latitudes and cooler in higher latitudes
• The amount of sunlight received per unit area

  • Near the equator - higher
  • Near the poles - lesser
• Average temperature in the region

  • Near the equator - warmer
  • Near the poles - colder
• The Earth revolve around the sun each year
• The Earth rotates on its axis each day
• The axis of rotation is pointed towards Polaris, the Northern star
• As the Earth orbits the sun , the tilt of the axis stayed line up with the north star
• The Earth is tilted 23.5 degree
• The Earth rotates counter-clockwise on its axis when viewed from polaris
• Equinox - the length of the day is equal to the length of the night.nThe sun's solar energy hits the equator at 90 degree angle
• Solstice - the longest day/shortest night (summer) or shortest day/longest night (winter)
• Equinox

  • Spring
  • autumn
• Spring equinox -march 21
• Autumn - September 22
• During the summer solstice in the Northern hemisphere, the earth's north pole is tilted towards the sun.
• During summer solstice the sunlight hits the earth's surface perpendicularly at 23.5 degree north latitude ( tropic of cancer)
• Summer solstice - tropic of cancer
• During summer solstice the place in 66.5 degree - 90 degree noth latitudes experience 6 months with sun light in the sky. The 66.5 north lat marks the Artic circle
• The 66.5 south latitudes or the Antarctic circle
• During northern winter solstice the north pole is tilted away from the sun
• During northern winter solstice the sunlight hits the Earths surface perpendicularly at 23.5 degree south latitude ( tropic of capricorn)
• During winter solstice the artic circle experience 6 months without a sun in the sky