"Extratropical Cyclone" (ETCS)
Vortices, which present extra tropical and sub polar cyclone, differ from
the Tropical cyclone under others by having other appearance and by containing
different cloud structures. Therefore they are regarded like two different
cloud structures.
The extra tropical cyclones look in Northern Hemisphere
as a comma.
In Southern Hemisphere the picture is reflected.
The size of the extra tropical cyclones reach several thousands of kilometres.
Cloud top height is up to 9 km.
They bring rainy weather.
The warm air, which flows in the high layer from the Tropics
toward the poles, is eastward diverted in Northern Hemisphere, due to
the Coriolis Effect. This causes there western prevailing winds. The near-surface
back-flowing cool polar air is diverted in western direction.
This opposite turbulent winds form in the middle latitudes low pressure
vortex, which in Northern Hemisphere moves eastward and has a vertical
axis, so that winds have nearly the same direction at the ground and in
the height.
This cloud structure contains a number of different types
of the other cloud structures.
Among them are convective cells structures necessarily.
The cirrus clouds are forerunners of a cyclonic warm front
coming soon. They seal to large and deeper stratus and cirrostratus clouds.
From the cirrostratus, due to advection, develop altostratus clouds, after
which nimbostratus clouds follow.
In the following cold front the upward displaced warm air cools down,
thus convective cumulus clouds develop.
The extra tropical cyclones are described detailed in literature
and internet.
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Glob. occurr. diagram
of 'Extratropical Cyclone' System 
