(2) The Latent Heat Unit, Or The Quantity Of Heat Required To Melt Or Vaporize Unit Mass Of A Standard Substance Under Given Conditions.
The corresponding intensity at the sun's surface is 4.62 X Io 4 as great, or 6.79 X Io 4 kilowatts per square metre = 7.88 X Io 4 horse-power per square yard - enough to melt a thickness of 13.3 metres (=39.6 ft.) of ice, or to vaporize 1.81 metres (=5.92 ft.) of water per minute.