Radiative properties of several kinds of soil

To examine the radative properties of the ground, some experiments have been made for three samples of the soils, viz., the sandy soil, ordinary loam and humous loam. The results of the measurements show that the thermal emissivities for these three kinds of the soils are 95, 97 and 99% respectively, compared to those values of the black body radiator. And, even if these soils contain some quantity of water and they are pretty wet, the above values of emissivities are not seriously altered. The thermal absorptivities of these soils are also very large as were expected from the Kirchhoff's law. The measured values of these absorptivities are 87, 95 and 99% for sandy soil, ordinary loam and humous loam respectively. The abosorptivities for solar radiation have been measured also, and it was found that they are almost the same in the case of thermal absorption in numerically. The measured values are 89, 97 and 99% for sandy soil, ordinary loam and humous loam respectively. Thus, we can say that the earth surface are almos nearly the grey radiator which is nearly the black surface, the emissivities and absorptivities of which are, in general, in the range of 99 and 100% compared to those of perfect radiator.