solar constant

American  

noun

1. the average rate at which radiant energy is received from the sun by the earth, equal to 1.94 small calories per minute per square centimeter of area perpendicular to the sun's rays, measured at a point outside the earth's atmosphere when the earth is at its mean distance from the sun.

---

solar constant British  

noun

1. the rate at which the sun's energy is received per unit area at the top of the earth's atmosphere when the sun is at its mean distance from the earth and atmospheric absorption has been corrected for. Its value is 1367 watts per square metre

---

solar constant Scientific  

1. The average amount of solar radiation received by the Earth's atmosphere, per unit area, when the Earth is at its mean distance from the Sun. It is equal to 1370 watts per square meter. Solar radiation varies with the Earth's distance from the Sun and with the appearance or decay of sunspots.

---

Etymology

Origin of solar constant

First recorded in 1865–70

Example Sentences

Experts have calculated that the tiny change in the solar constant detected by Solar Max can supply less than a millionth of the energy needed to produce the observed changes in weather.

From Time Magazine Archive

Reduced to more comprehensible terms, solar radiation amounts to 1.35 kW falling on every square meter of earth, a number that scientists call the solar constant.

From Time Magazine Archive

These changes in the solar constant appear to move in cycles of about three years.

From Time Magazine Archive

The finding strongly suggests that solar radiation varies with the sunspot cycle and that the solar constant is not that constant after all.

From Time Magazine Archive

The Platform could make much more precise measurements of the solar constant than could be obtained below.

From Space Tug by Leinster, Murray