Climate is the average and variations of weather over long periods of time. Climate zones can be defined using parameters such as temperature and rainfall. Paleoclimatology focuses on ancient climate information derived from sediment found in lake beds, ice cores, as well as various fauna and flora including tree rings and coral. Climate models can be used to determine the amount of climate change anticipated in the future.

US Temps



CANADA



EUROPE

Jet streams are fast flowing, relatively narrow air currents found in the atmosphere at around 11 kilometres (36,000 ft) above the surface of the Earth, just under the tropopause. They form at the boundaries of adjacent air masses with significant differences in temperature, such as of the polar region and the warmer air to the south. The jet stream is mainly found in the Stratosphere.

The major jet streams are westerly winds (flowing west to east) in both the Northern Hemisphere and the Southern Hemisphere, although in the summer, easterly jets can form in tropical regions. The path of the jet typically has a meandering shape, and these meanders themselves propagate east, at lower speeds than that of the actual wind within the flow. The theory of Rossby waves provides the accepted explanation for propagation of the meanders; Rossby waves propagate westward with respect to the flow in which they are embedded, but relative to the ground, they migrate eastward across the globe.

US SNOW COVERAGE



NORTHER HEMISPHERE