Radiative Balance Solar radiation received

Above Earth's atmosphere, the amount of radiation, S, passing through a plane normal to the direction of the sun (e.g., the plane in the lower panel of figure 1.1) is about 1,366 W/m2. (A watt is a joule per second, so this is a rate at which energy is arriving.) However, at any given time, half of earth is pointed away from the sun, so that on average Earth receives much less radiation than this. How much less? Let us first calculate how much radiation earth receives in total every second. The total amount is S multiplied by the area of a disk that has the same radius as earth (figure 1.1). if earth's radius is a, then the area of the disk is A = na2, so that the rate of total radiation received is Sna2. over a 24-hour period, this radiation is spread out over the entire surface of earth, although not, of course, uniformly. Now, earth is almost a sphere of

Incoming solar radiation -> ""

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