The Weather Handbook by Alan Watts

Author:Alan Watts
Language: eng
Format: epub
ISBN: 9781472913883
Publisher: Bloomsbury Publishing
Published: 2014-06-13T00:00:00+00:00

towards its afternoon maximum speed so the scale of these variations will decrease. The wind will be stronger but the shifts within it will seem less noticeable.

Winds in the afternoon

The couple of hours after when the sun is on the meridian (local noon) will see the wind at its strongest on a normal day. How variable the afternoon wind becomes depends on its strength and what kind of cloud cover there is.

If, despite the expected increase in speed, the afternoon wind remains sluggish then either you have total low cloud cover or you have no low cloud cover. In the latter case a very strong subsidence inversion is inhibiting the growth of thermals and stopping the air being mixed up through any great depth. If the thermals cannot bring down stronger wind from above to ginger-up the surface wind the latter remains somnolent. There will often be strange shifts of direction as well.

With moderate winds if there should be Cu clouds, the wind will be fairly variable and if these have not grown into anything bigger then it is an inversion near their tops which is preventing them growing. The wind in this case will not do anything odd and will just sink into the evening as the heap clouds disperse.

If the day’s wind is strong in the morning then it will usually be quite a bit stronger by the afternoon. This is particularly so if the cloud cover is broken.

If it is a total cover of Sc or other layer cloud the increase of speed into the afternoon may not be marked but when the afternoon clouds are heap ones the puffs may be too much for some sailors to handle.

There may not be a sea-breeze when the wind is blowing at moderate strength from land to sea but the opposition of the sea-breeze force to the established wind can make the latter go down with the afternoon rather than up. However, should the day be one of sunshine and heap clouds (or maybe just sunshine) and the wind blows from sea to land the addition of the sea-breeze effect can make the wind in the afternoon exceed the forecast speed by a substantial margin. Then big rollers come onto the beach and children may have to be restrained from being too venturesome.

On such days learners and improvers in dinghies and on boards should go for the morning before the wind really gets up and decide to do something else in the afternoon. They can also try the evening but evening winds are notoriously fickle and not good for beginners.

The afternoon wind will begin to really drop away once the inversion begins to set in. This usually occurs around 16.00–17.00 and then the wind

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