Absolute cavity pyrgeometer

A method for measuring the absolute atmospheric long-wave irradiance comprising:

• orienting an absolute cavity pyrgeometer to receive and measure atmospheric long-wave irradiance, the absolute cavity pyrgeometer comprising at least a concentrator, a thermopile and a temperature controller in thermal communication with the thermopile;
• cooling the thermopile by lowering a temperature of the temperature controller;
• obtaining one or more measurements from the absolute cavity pyrgeometer;
• calculating the sensitivity of the thermopile from the one or more measurements from the absolute cavity pyrgeometer;
• and
• calculating the atmospheric long-wave irradiance from the one or more measurements from the absolute cavity pyrgeometer and the calculated sensitivity of the thermopile.

A system for measuring absolute atmospheric long-wave irradiance comprising:

• a computing device comprising:
• a processor in communication with a computer-readable medium;
• and
• an absolute cavity pyrgeometer comprising:
• a thermopile configured to detect atmospheric long-wave irradiance and to output a voltage related to the detected atmospheric long-wave irradiance to the computer-readable medium of the computing device;
• a concentrator configured to reflect atmospheric long-wave irradiance to the surface of the thermopile;
• and
• a temperature controller in thermal communication with the thermopile configured to control the temperature of at least one surface of the thermopile.