Eppley pyrheliometer

Eppley pyrheliometer

[′ep·lē ¦pīr‚hē·lē′äm·əd·ər]
(engineering)
A pyrheliometer of the thermoelectric type; radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lampblack; a system of thermocouples (thermopile) is used to measure the temperature difference between the rings; attachments are provided so that measurements of direct and diffuse solar radiation may be obtained.