Albedo

AlbedoOne of the characteristics possessed by any material body is albedo.Albedo characterizes the reflective properties of body surface. This is the ratio of radiation flow scattered by the surface to the flow incident on it. It comes from the Latin word "albus" -- white. You can guess that this value has no dimension.But what kind of radiation is this?Actually, it can be radiation in different ranges -- visible, infrared and ultraviolet. Accordingly, albedo will be determined for each range.For example, characteristics of reflection properties of infrared rays specifically. There are several types of albedo for optical range. The true one is the ratio of flow, which is scattered by flat surface in all directions, to the flow incident on this surface.Visible albedo is the ratio of surface brightness illuminated by parallel beam of rays to brightness of absolutely white surface.In astronomy there are also concepts of geometric and spherical albedo. Names of integral or power albedo belong to characteristics for the whole flow of radiation in different ranges.Albedo value depends on surface properties, its material and color. And different albedo of different materials and bodies, in its turn, can affect many things.The highest values have clouds and snow -- 0.9. This means that up to 90% of radiation is scattered. Therefore, snow melts slowly, even in bright sunlight. In contrast, albedo of water and plowed black earth is very low -- about 0.05 -- these are heat capacious surfaces. Albedo of trees, grass and sand stand between these values. In general our planet reflects about 40% of incoming radiation. Perhaps that is why it looks so bright and beautiful from the Moon. Albedo of the Moon and other planets with no atmosphere is rather low -- 0.07. In planets with atmosphere this value is much higher -- about 0.6.As it is clear already, the albedo concept is widely used in astronomy to learn about other planets. The same relates to climatology. Without even thinking we choose from wardrobe clothes with the highest albedo on a hot sunny day, i.e. the lightest -- so that it is not so hot.