An abiotic factor is any of a number of the non-living components of a habitat. Abiotic factors can be grouped into the categories of meteorology, soil, air pollution, micro-topographic features, water availability and water quality. In terms of meteorological factors, the primary abiotic factors can be construed to be temperature, precipitation, wind velocity, solar insolation and humidity. It should be noted that statistical variation and seasonal variation of these basic parameters can be important elements of the habitat description as well as the temporal correlation of these variables; for example, for certain amphibian species, it is not only the average annual rainfall which is important to reproductive success, but especially the timing of rainfall that occurs in breeding season or the rainfall that occurs within the temperature optima for breeding. In addition the thawing timing of ponds can also be significant.