Image: Polar vortex enters northern US
Tuesday, January 7, 2014 - 09:00
in Earth & Climate
The polar vortex is a whirling and persistent large area of low pressure, found typically over both North and South poles. The northern polar vortex was pushing southward over western Wisconsin and eastern Minnesota on Monday, Jan. 6, 2014, and was bringing frigid temperatures to half of the continental United States. It is expected to move northward back over Canada toward the end of the week.