1. Altitude of the Sun- Solar Altitude
The Sun is at its maximum daily altitude at solar noon
Generally, the higher the latitude, the lower the altitude of the sun in the sky at noon
Solar altitude is
lowest at the poles
Solar altitude is
highest near equator
Solar altitude is
lowest at the poles

2. Angle of Insolation: Incoming Solar Radiation (sunlight)
The angle the Sun’s rays hit the Earth
Higher the latitude, the lower the angle of insolation
Insolation intensity is
Least at the poles
Insolation intensity is
Greatest near equator
Insolation intensity is
Least at the poles

3. The Sun’s Vertical Ray Sun has 900 angle of insolation
This means that the Sun is directly overhead
We NEVER get the vertical ray in New York!
Our latitude is 43.5oN
Vertical Ray is here on June 21st
Vertical Ray is here on March 22nd and Sept 22nd
Vertical Ray is here on Dec 22nd

4. Altitude of the Sun For New York State
June 21st is the first day of summer
On June 21st, we have solar noon altitude = 71.5o
The observer has to look SOUTH at noon

5. Altitude of the Sun For New York State
March 22nd is the first day of spring
September 22nd is the first day of autumn
On these days solar noon altitude = 47o

6. Altitude of the Sun For New York State
December 22nd is the first day of winter
On December 22nd, the solar noon altitude = 23.5o

7. Earth’s Revolution around the Sun
Summer: North Pole tilted toward sun
This makes it appear HIGH in the sky for us
Winter: North Pole tilted 23.5o away from sun
This makes it appear low in the sky for us

8. Earth’s Revolution around the Sun
Fall and Spring: Pole NOT TILTED toward or away
Sun altitude is higher than winter but lower than summer

9. SUMMER HIGHER ALTITUDE/HIGH ANGLE

10. WINTER LOWER ALTITUDE/LOW ANGLE

11. June 21st Summer Solstice
North Pole tilted toward sun
Sun at zenith on 23.5oN (Tropic of Cancer)
Highest angle of insolation for NY
Sun is most intense, which makes it warmer in the summer
Because of the earth’s spherical shape, on any particular date, there is just 1 place where insolation (incoming solar radiation) is at an angle of 90°. All other places are less than 90°.
Does the 90° ever reach the United States?
An observer in New York State will never see the Sun directly overhead.

12. December21st Winter Solstice
North Pole away from sun
Sun at zenith on 23.5oS (Tropic of Capricorn)
Lowest angle of insolation for NY
Sun is least intense, which makes it colder in the winter
900
Because of the earth’s spherical shape, on any particular date, there is just 1 place where insolation (incoming solar radiation) is at an angle of 90°. All other places are less than 90°.
Does the 90° ever reach the United States?
An observer in New York State will never see the Sun directly overhead.

13. September 22nd Fall Equinox
Neither pole tilted toward sun
Sun at zenith on 0oS (Equator)
Angle of insolation for NY = 47o
Fall equinox is also called autumnal equinox
Spring equinox is exactly the same
900
Because of the earth’s spherical shape, on any particular date, there is just 1 place where insolation (incoming solar radiation) is at an angle of 90°. All other places are less than 90°.
Does the 90° ever reach the United States?
An observer in New York State will never see the Sun directly overhead.

14. The Intensity of Insolation
Sun’s energy is MOST INTENSE at high angle
Most intense in TROPICS: between 23.5oN and 23.5oS
Most intense at NOON: Highest during the day
Sun is directly overhead in
the tropics so is most intense!