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
2)
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:
1)
Solstice : Sun stands still ( does not move any further North or South)
Summer: day of maximum daylight hours
Winter: day of minimum daylight hours
2)
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
Autumnal Equinox
-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
Vernal Equinox
-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