Jetstream For The History Books
A picture for the history books was taken by European weather satellite Meteosat. On March, 30th 2013 the jetstream was extremely far south. Low pressure systems were hoovering across North Africa, the furthest easterly of it above Egypt! A far south jetstream is specific for deep winter but according to the calendar we have springtime. The jetstream is a narrow band of strong west to east winds in the upper troposphere making and moving the high and low pressure weather systems. It is driven by differences in temperature between polar and tropical air leading to differences in air pressure increasing with altitude. If the difference in temperature exceeds a critical threshold, jetstream becomes wavy (Rossby waves).
Jens Christian Heuer