The Garden Guide

Book: Gardening Science - Soils, Manure and the Environment
Chapter: Chapter 3: Heat, Light and Electricity

Clouds and solar heat

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1332. Dense clouds, near the earth, reflect back the heat they receive from it by radiation. But similar dense clouds, if very high, though they equally intercept the communication of the earth with the sky, yet being, from their elevated situation, colder than the earth, will radiate to it less heat than they receive from it, and may, consequently, admit of bodies on its surface becoming several degrees colder than the air. Islands, and parts of continents close to the sea, being, by their situations, subject to a cloudy sky, will, from the smaller quantity of heat lost by them through radiation to the heavens, at night, in addition to the reasons commonly assigned, be less cold in winter than countries considerably distant from any ocean. But the chief cause why islands, and the coasts of the ocean, are more temperate than continents and inland situations, is, that the temperature of the ocean a little from the surface, and where not cooled by contact with ice, is very uniformly about 54ᆭ Fahr. in all latitudes. The ocean is the great equaliser of heat. (T.)