EUMeTrain: Water Vapour CAL Module - Water Vapour Images And Related Numerical Parameters

Wind: Jet streams

Upper level jet streams occur just below the dynamical tropopause between different air masses. When an area of low tropopause catches a jet stream, they interact and the wind field of the anomaly is added to the jet creating a core of maximum wind speed and intensifying the disturbance.

"Tropopause folding" occurs when the stable stratospheric air intrudes under tropospheric air under the jet stream. It can be seen as a sharp gradient in the grey shades of water vapour images.

If you look at the wv image alone (see below), where you can get an indication of the jet streaks? There are two correct areas!

If you have correctly idetified the areas, you can see the answer in this additional image.