Unit 2: Weather Dynamics
Worksheet 11: Seasons and the Angle of the Sun
Much of the Earth’s weather, especially our changing seasons are caused by:
1) Tilt of the Earth
Earth is tilted at 23.5 degrees on its axis
This rotation is what caused day and night
Earth’s revolution around the sun
It takes 365.25 days for the Earth to make a complete revolution around the sun.
Sub-solar point the point where the sun’s rays strike the earth at a 90 degree angle.
The beginning of each season is marked by:
Solstice : Sun stands still ( does not move any further North or South)
Summer: day of maximum daylight hours
Winter: day of minimum daylight hours
Equinox Day and night are equal length
The following important dates on the next slides are for the Northern Hemisphere ( the opposite occurs in Southern Hemisphere)
Summer Solstice :
-June 21, the first day of summer
-Northern Hemisphere is at its maximum tilt toward the sun
-It is the maximum daylight period
-Sun is over the Tropic of Cancer (Northern Hemisphere)
-So the sun’s ray are hitting the Northern Hemisphere most directly .
-Sun’s rays have their maximum intensity since they are concentrated over a smaller surface
-September 23, the first day of fall
-Sun in directly over the equator
-The sun is above the horizon for 12 hours and below the horizon for 12 hours
Winter Solstice :
-occurs December 21 => the first day of winter
-Northern Hemisphere is at its maximum tilt away from the sun
-Minimum daylight period ( Short day or long night)
-Sun is over the Tropic of Capricorn (southern Hemisphere). So the sun’s ray are hitting the
Northern Hemisphere at a steep angle.
-Sun’s rays have their minimum intensity since they are spread over a larger surface
-Occurs on March 21.
-On this day the solar point is directly over the equator.
-All parts of the earth will have a 12 hour day and a 12 hour night. It is Spring in the northern hemisphere. 1
PART A: Multiple