Weather refers to the atmospheric conditions at a certain time or over a certain short period in a given area. It is described by a number of meteorological phenomena which include atmospheric pressure, wind speed and direction, temperature, humidity, sunshine, cloudiness, and precipitation.

The effects of weather are felt by all life forms on Earth, and weather is also a major contributor in shaping Earth's lithosphere (surface crust). The impact of weather is most pronounced during the occurrence of extreme weather situations, such as prolonged periods of heat, cold, rain, drought and smog conditions. In addition shorter but intense events such as hurricanes, tornadoes, winter blizzards, freezing rain, and floods also produce often dramatic effects on both the social and geologic landscape. The concern to reduce the impact of weather on public health and property provides an important motivation for the continued efforts by meteorologists and scientists to...