In sciences such as physics, geography, astronomy, meteorology and statistics, the term scale or spatial scale is used for describing or classifying with large approximation the extent or size of a length, distance, or area studied or described. For instance, in physics an object or phenomenon can be called microscopic if too small to be visible. In climatology, a micro-climate is a climate which might occur in a mountain, valley, or near a lake shore, whereas in statistics a megatrend is a political, social, economical, environmental, or technological trend which involves the whole planet or is supposed to last a very large amount of time.