What is Solar Noon?
Solar noon is the point during the day at which the sun reaches its highest point in the sky and will proceed to descend until it sets.
- Does not generally occur at 12pm.
- Where the terms ‘am’ and ‘pm’ originate.
- In terms of timing, it happens earlier at locations east of you and later at locations west of you.
Understanding Solar Noon
Solar noon is the point at which the sun reaches its highest point in the sky at a particular location – confusingly, this generally does not occur at 12pm.
Your local meridian is an imaginary line that can be traced from north to south across the sky overhead. The point at which the sun crosses that line (traveling from East to West) is the highest point it will get on that day and is called solar noon, midday, or local noon. It is also the point at which the sun will cast its shortest shadow, and is the origin of the terms ante meridiem (a.m.) and post meridiem (p.m.).
At the equator, the sun is directly overhead at chronological noon on the equinoxes, at the Tropic of Cancer on the June Solstice, and at the Tropic of Capricorn on the December Solstice.
In terms of just WHEN solar noon is, well that gets a little trickier. Due to the tilt of the earth and where you are on the planet, solar noon shifts. It happens a little earlier in locations east of your position on the planet, and a little later in locations west of you.
Solar Constant – The constant rate at which solar radiation hits the surface of the earth, which is accepted to be approximately 1,388 watts per square meter.
Full Sun – An area that gets more than 6 hours of direct sunlight per day.
Peak Sun Hours – Defined as the number of one-hour units of time where the intensity of sunlight is at least 1kW per square meter.