Height of storm surge (m)
~ 1.5 Damage mainly to trees, shrubbery and unanchored mobile homes
~ 2.0-2.5 Some trees blown down
Major damage to exposed mobile homes Some damage to roofs of buildings
~ 2.5^.0 Foliage removed from trees; large trees blown down Mobile homes destroyed Some structural damage to small buildings
~ 4.0-5.5 All signs blown down
Extensive damage to roofs, windows and doors
Complete destruction of mobile homes
Flooding inland as far as 10 km
Major damage to lower floors of structures near shore
> 5.5 Severe damage to windows and doors
Extensive damage to roofs of homes and industrial buildings Small buildings overturned and blown away Major damage to lower floors of all structures less than 4.5 m above sea-level within 500 m of the shore
Water spouts are similar to cyclones, in that they are funnel-shaped vortices of air with very low pressures at their centres, so that air and water spiral rapidly inwards and upwards. The funnels extend from the sea-surface to the 'parent' clouds that travel with them (see Figure 2.19). They whip up a certain amount of spray from the sea-surface but are visible mainly because the reduction of pressure within them leads to adiabatic expansion and cooling which causes atmospheric water vapour to condense.
Water spouts are much smaller-scale phenomena than cyclones. They range from a few metres to a few hundred metres in diameter, and they rarely last more than fifteen minutes. Unlike cyclones they are not confined to the tropics, although they occur most frequently there, usually in the spring and early summer. They are particularly common over the Bay of Bengal and the Gulf of Mexico, and also occur frequently in the Mediterranean.
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