A plane with protrusions is analyzed as a model for remote sensing of the earth's surface and for absorption of solar irradiance at the surface. The model is aimed at representing arid regions where plants form isolated clumps with large interstices of bare soil. The protrusions (plants) are regarded as thin vertical cylinders, and the key parameter s (which is dimensionless) is the sum of vertical cross sections of protrusions over a unit area. Remote sensing from a satellite indicates the plausibility of the model, inasmuch as the model closely reproduces, as a function of the solar zenith angle, the spectral reflectivities measured by LANDSAT over an arid steppe. The explicit expressions for the hemisphere reflectivities indicate a strong dependence of the surface reflectivity of such terrain on the zenith angle. The heating of the protrusions is a very significant part of the daily total surface heating when the noon sun is low. The interactions with the atmosphere are generally different for the protrusions and for the planar surface of the soil. The difference in the interactions is especially pronounced in the arid steppe, inasmuch as the effective thermal inertia of the protrusions (mostly dry bushes) in heat transfer to the atmosphere is very low. This low thermal inertia, and therefore nearly immediate transfer to the atmosphere of the solar irradiance absorbed by the protrusions, is indicated by radiation temperature measurments of the protrusions and of the soil.