NEWS - NOTICE
meteorologically speaking, with the end of August, there is also the end of summer. Almost concurrently with this deadline, in the last days of August, in NW Italy the heat has given way to a dry wind, the Fohn, and maximum temperatures a bit milder and minimum sottomedia also for the period.
Where did this change? The question is not so foolish for anyone to forecast not to chew anything and will try to explain trying to use the term more simple and clear as possible. Let's see what happened and why the cool came without a storm, as someone asked me.
Looking at the weather patterns are known as the day on August 29 a trough approaches and enters the North Italy from N-NE (see map at 500 hPa in the following as an area with gpt-geopotential-height children, associated with the scale of cooler colors, from red / orange pre-existing switches to yellow on the way).
Broadly we can say that a trough is associated with a worsening of the time, especially in the area that lies to the right of the trough itself. Besides the axis of the trough, moving toward the left generally has better weather. In our case this axis is far more to the east of NW Italy and this has meant that the current share of the NW NW Italy are rotated resulting in the genesis of a dry wind from the Alps fall that allowed sunny days and clear.
In fact, the air encounters in its journey across the Alps to the NW to the mountain range. To overcome it is forced to rise rapidly upward, and then condenses into clouds that can easily generate showers (this is on the windward side). When passing the mountains, quickly falls to the ground after losing its moisture content, and compressing, tends to warm up.
Looking at these maps of theta-and give us an idea about the content of moisture in the air, we can quickly understand the difference between the air mass on Friday 27 at 14 pm and that of 29 at the same time.
The 27 values \u200b\u200bare quite high, as seen in scale side, and then the moisture content high altitude of 850 hPa (about 1500m).
29, we have far moisture content.
The air mass arriving across the Alps, however, is colder than this pre-existing allowed a lowering of temperature, but without storms. Complicit in what the very dry wind which inhibited the formation of any signs, even in a short time dissipating any energy in the spot that could be exploited for the time ( CAPE).
Warning, this does not mean in an absolute sense that the presence of dry air inhibits the formation of storms, in fact sometimes it is the responsibility of the Convention, even violent as in the case of the formation of Dryline (dry lines in fact). These lines act just dried when they meet with more humid air masses, and then there is a sharp contrast to humidity. Classics in Northern Italy are the Dryline acting from the area of \u200b\u200bGarda to the east: in these areas there has been a flourishing of cumulonimbus clouds, while to the west the sky was clear and sunny, maybe crossed only by cumuletti harmless.
is the sky of the beautiful day of 29 August.
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