Which city receives the most constant insolation year round? WHY?

Why do THESE THREE THINGS change? Angle of insolation determines how Earth heats. (greater angle = greater energy) What determines the angle of insolation? Season, Latitude, Time of Day Why do THESE THREE THINGS change?

One reason is Earth’s 23.5o tilt. The other reason is how Earth moves. NOT LIKE THAT!

Earth has several motions. We will only consider two : ROTATION- spinning on its own axis. REVOLUTION- orbiting around the sun.

23h 56m 4s 365.26 d

Rotation and revolution are independent movements that occur at the same time!

Rotation Earlier (not yet noon) Later (past noon) 12 Noon

Rotation Not Facing Sun Facing Sun

Rotation SUN MOON

Rotation 15o /hr !

Rotation is responsible for: Day and Night Cycle Time zones and longitude Celestial objects moving through sky (moon, stars, planets, etc.) Coriolis Effect (we’ll discuss later in year) WHICH ONE CHANGES THE ANGLE OF INSOLATION?

Revolution

Revolution

Revolution

Revolution Sun in January photo. Sun in July photo.

Revolution is responsible for Seasons Visibility of constellations Apparent size of sun WHICH ONE CHANGES THE ANGLE OF INSOLATION?

In New York State, summer is warmer than winter because in summer New York has (1) fewer hours of daylight and receives low angle insolation (2) fewer hours of daylight and receives high angle (3) more hours of daylight and receives low-angle (4) more hours of daylight and receives high angle insolation