Cape Effect

[j dragon]

Here is a newbe question, remember newbes are here to make "old salts" look good. I am reading Bruce Van Sant's "Passages South", and he mentions several times the CAPE EFFECT. He does not explain it and I can not find an exact definition. Thanks in advance, Jim

[osirissail]

I don't remember what Bruce put in his book, but as you approach an island say from the north with an east wind, there is an acceleration zone up to 5 nm off the northern end of the island that lasts until you are behind the island.
- - The winds "wrap around" the island and the direction of the wind changes accordingly. Also the "wrapping around" tends to increase the wind velocity while you are in "cape effect" and then once you get behind the island the wind decreases dramatically. You can see the effect on the surface of the water as you approach.

[mrohr]

Stable air (cooler,drier) does not readily go up and over an obstacle it encounters in it's travels. It will go around instead and must accelerate as it does so. the higher the headland the greater the effect.




I think this is often demonstrated between the Hawiian Islands.Allan Watts calls this the steering effect.

[barnakiel]

This and then the waves action on top. Just stay well clear of capes and you are better off.

(BTW Over a spectacular flat island the wind may actually curve 'in' at the cape on a hot day. I believe this is because the air over the island is lifted as it gets heated by the land. Then cooler air is sucked in. But this here is not the cape effect the author had in mind.)

b.

[foolishsailor]

In the southern ocean the wind and swells go relatively unimpeded around the globe except for two squash zones, Cape Horn and Cape of Good Hope, also known as Cape of Storms. This create acceleration zones also known as the cape effect. You also tend to have large volum high speed currents coming down the coastlines leading to these capes.