Here, “micrometerogological” variations refer to spatial variations of atmospheric conditions near the surface due to small-scale variations of terrain, vegetation and soil on horizontal scales of a few km or smaller.  The horizontal scale of the influence of the surface generally increases with height (sometimes referred to as the surface footprint).  For example, the air closest to the surface might be influenced by individual bushes or surface features on a horizontal scale of 1 m.   At 10 m above the surface the area of upwind surface influence might be on the order of 10 m to 100 m across depending on the wind speed and a number of other factors.

In an effort to achieve physical understanding, the literature concentrates on well defined spatial variations, such as differences between irrigated and non-irrigated surfaces and well defined uniform slopes.  Most of the Earth’s surface is more complex and the attendant micrometeorology is poorly understood.