Airmass Thunderstorm

Till July 22nd, I already counted 15 thunderstorm-days this month, which is above normal. Most of these thunderstorms are of the type which meteorologists describe with the term airmass thunderstorms.




Airmass thunderstorms develop in the course of the day due to the heating of the surface, and rapidly dye out after sunset.
The life cycle of one cell takes typically 30 to 50 minutes. They usually are not strong enough to produce severe weather.


A true single cell storm is actually quite rare. Even with isolated storms in weak vertical wind shear, the gust front on one cell often triggers the growth of another cell some distance away.
Single cells in this way form the building blocks of larger convective systems.




Thunderstorm in the direction of Bistrita, Romania. 21 July 2010.









In the late afternoon/early evening of 21 july, such a single cell developed exactly over my location. Since there was hardly any wind on all levels of the atmosphere, it didn't move and dropped it's precipitation right on the village where I live.



Radar-image of 21 July 2010, 18:40 local time.



VIS satellite-image of 21 July 2010, 19:15 local time.












And here the result..... more than 20 mm of rain in about three quarter of an hour.
















One day later (22 July) another round of airmass thunderstorms produced some photogenic oportunities:



Growing thunderheads in easterly direction.



Nice downdraft from a cell in the north. It produced moderate gusts (estimated 25 kt) when reaching my location.