15 | 11 | 2018

Jet Stream maps

Current jet stream analysis

Five day animation of jet stream

 300mb/hPa Jet stream data/graphics courtesy of San Francisco State University

250mb/hPa Jet Stream

 

 

 Wind Velocity Scale

250mb/hPa data courtesy of Cameron Beccario's Earth wind map - http://earth.nullschool.net

What is a jet stream?

A jet stream is a fast flowing, narrow, high altitude air current.  They occur at the transition between the troposphere and stratosphere (tropopause) and typically flow from west to east although they can split and reverse direction.  They are typically a few hundred miles in width and less than three miles in height and flow for very long distances although they can be discontinuous.  The large meanders are caused by variations in the coriolis force at different latitudes and are known as Rossby waves.  Polar jet streams flow roughly 4 to 7.5 miles above sea level while sub tropical jet streams are between 6 and 10 miles above sea level.  Polar jet streams are stronger and may have wind speeds as high as 200 mph.

They have a large influence on global and hence regional weather, affecting the direction of cyclonic storms and polar air flow.  Recent extreme winter conditions and summer floods in the UK have been attributed to the polar jet looping south over Britain.