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

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

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

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

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

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

Earth’s Revolution around the Sun Summer: North Pole tilted 23.50 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

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

SUMMER HIGHER ALTITUDE/HIGH ANGLE

WINTER LOWER ALTITUDE/LOW ANGLE

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.

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.

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.

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!