What affects how heat is distributed over the surface of Earth?

I.  Sun angle
    A.  The angle at which the sun's rays reach Earth is directly related to the intensity of sunlight at the surface.  Think of the flashlight experiment in class.
          1.  At high angles ( 65^o-90^o) the sun's radiation is most intense.  This is why noon or the early afternoon is often the warmest time of day.
          2.  At low angles (5^o-30^o for instance) the sun's radiation is more diffuse and spread out, compared to the typical noon time sun.  Mornings and evenings are cooler than midday hours for this reason.
    B.  Sun is highest in the sky at noon, but this highest point (zenith) varies by latitude and by season of the year.
          1.  Earth is tilted by 23.5^o from a position perpendicular to its orbital plane.  Earth's tilt remains fixed as it orbits the sun.
          2.  As Earth orbits the sun, the north pole tilts toward the sun part of the year, and away from the sun part of the year.
          3.  The sun rays shine down perpendicularly at a different latitude each day because of this tilt and its orbit around the sun.  Where the sun's rays shine down perpendicularly is where Earth becomes warmer.
            a.  On June 21-22, the Sun's perpendicular rays (witnessed by 90^o position of sun at noon) shine down at 23.5^o N latitude (Tropic of Cancer).
                b.  From June to September 21, the Sun's perpendicular rays migrate from 23.5^o N latitude to the equator (0^o latitude).
                c.  From September to December 21, the Sun's perpendicular rays migrate from the equator to 23.5^o S latitude (Tropic of Capricorn).
                d.  From December to March 21, the Sun's perpendicular rays migrate from 23.5^o S latitude to the equator.

    C.  Sun angle also relates to the thickness of the atmosphere that the sun's rays must pass to make it to Earth's surface.
          1.  When sun is at a high angle to Earth's surface, sun's rays pass through less of Earth's atmosphere.
          2.  When sun is at a low angle to Earth's surface, sun's rays pass through more of Earth's atmosphere.

II.  Duration of sunlight.  Length of daylight varies seasonally.
    A.  As the Sun's vertical rays migrate into the N. hemisphere, the length of daylight for the N. hemisphere increases. 
           1.  The day of longest daylight for N. hemisphere occurs when Sun's vertical rays are positioned over the Tropic of Cancer.
          2.  All points north of the Arctic circle (66.5^o N latitude) receive 24 hours of daylight at this time (June 21, June solstice).  24 hours of daylight has the sun positioned close to the horizon throughout the day, like a permanent sunrise or sunset.
    B.  When the Sun's vertical rays are positioned over the equator (September 21, March 21), all points on Earth receive 12 hours of daylight, 12 hours of night.  Such a day is called an equinox (latin for "equal night").
    C.  As the Sun's vertical rays migrate into the S. hemisphere, the length of daylight for the N. hemisphere decreases.
          1.  The day of shortest daylight for N. hemisphere occurs when Sun's vertical rays are positioned over the Tropic of Capricorn.
          2.  All points north of the Arctic circle receive 24 hours of night on this day (December 21, December solstice).
    D.  Seasons and seasonal conditions are opposite across the equator.  While it is summer in N. hemisphere, it is winter in S. hemisphere, and vice versa.
    E.  Higher latitudes experience greater lengths of daylight and night.  Lower latitudes experience more consistent lengths of daylight throughout the year.  The equator always experiences 12 hours of daylight every day of the year.