What's the Tropopause?

	The jet stream is a river of fast-flowing air from west to east in the midlatitude upper troposphere (9-12 km above sea level). Magnitude [m/s] of the observed montly-mean winds at 250hPa in February 2003.
The jet lies on a surface called the tropopause, which separates the troposphere from the stratosphere. Magnitude of the westerly wind (color shading) and potential temperature (contours) cutting vertically through the atmosphere along the black line (60oW) in the previous figure.
	The tropopause slopes downward from equator to pole. The tropopause is not static -- its movement is related to day-to-day weather variations. The dynamical tropopause, defined as a surface of constant potential vorticity (PV), for February 2003. PV is a measure of the potential for an air parcel to locally rotate about a vertical axis:

Front page What's the Tropopause? (you're here) Tropopause Variations and Cyclogenesis? Case Study of a Severe Storm? How a Full PV Weather Map is Made?