The fraction of sunlight retained as net radiation in Hawaii

Both estimated and measured values of net radiation over several different surfaces established the retention of approximately two-thirds of the sunlight as net radiation for stations at low elevations in Hawaii. This high retention of sunlight was a consequence of both low reflectance and a very low heating coefficient (change of long-wave net radiation with change in total net radiation). The persistent high elevation of the sun and the efficient convective heat sink formed by the maritime air helped to account for this large retention of sunlight as net radiation. The mineralogic composition of the soil and the leaf habit of the vegetative cover contributed to the low reflectance from these surfaces. Since this net radiation can be used to heat the soil, plants, and air, and to evaporate water, the heat and moisture budgets of a surface in the maritime tropics may differ markedly from those of a surface in the temperate latitudes under similar solar radiation.