Wind energy is power produced by the movement of air. Since early recorded history, people have been harnessing the energy of the wind to, for example, mill grain and pump water. The energy resources contained in the wind in the United States are well known and mapped in detail. It is clear that air movement plays a critical role in transporting the energy of the lower atmosphere, bringing the warming influences of spring and summer and the cold chill of winter, and wind and air currents are fundamental to how nature functions. The terms wind energy and wind power reflect the process by which the wind is used to generate mechanical power or electricity. The Wind Energy Resource Atlas contains data from airports in the United States and makes wind data summaries available. Typical activities during the wind energy facility construction phase include ground clearing, grading, excavation, blasting, trenching, vehicular and pedestrian traffic, and drilling.