NASA EXPLAINS DUST BOWL DROUGHT. NASA scientists have an explanation for one of the worst climatic events in the history of the United States, the Dust Bowl drought, which devastated the Great Plains and all but dried up an already depressed American economy in the 1930's.
The short run [in economics] is a period of time in which the quantity of at least one input is fixed and the quantities of the other inputs can be varied. The long run is a period of time in which the quantities of all inputs can be varied.
In economics the short run and the long run are not defined by an arbitrary amount of time. Instead the short run is the period when at least one factor of production is fixed and cannot be changed. Similarly the long run period is the period when all factors of production are variable. Having said that, the law of diminishing returns arises in the short run because of the at least one fixed factors of production. In the short run the size of a factory, the number of PC's in a office, the area on a agricultural field and so on are fixed.