Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Visible range of the ASTM G173-03 solar irradiance spectrum, measured at a global tilt of 37° pointing to the sun (blue). The solar irradiance spectrum when not staring directly at the sun, including light scattered by the atmosphere and light reflected off the earth’s surface, is also shown (red).
