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Wind Direction
Posted: Wed Jan 18, 2006 3:53 pm
by DieselFan
How does one make the most of wind direction? Eg from the ballooning thread, I can fly at 6000 with a tailwind towards Dbn from Jhb and then over Pmb goto 8000 to keep the tailwind? Is this possible?
I so often hear of people saying we had a headwind, so why don't they go up or down till they get a tailwind?
Posted: Wed Jan 18, 2006 4:23 pm
by Morph
Yes, when we fly cross countries we try different altitudes to get the lowest headwind/highest tailwind effect. Generally speaking the higher you go the faster the wind, and the wind direction changes as you climb. At low levels ,under 2500ft AGL the wind if affected by the rotation of the earth and the direction bends away from it's normal path by up to 30 deg over land and 15deg over water. This effect is called the Coriolus effect. Additionally the friction caused by mountains, trees etc further influences/reduces the speed of the wind.
It is possible to get a complete change in the direction of the wind between two layers. If you move from one to the other you could experience severe wind shear which is not nice.
If you call the weather office or go to
http://www.weathersa.co.za you should be able to give you fairly accurate readings in this regard.
Posted: Wed Jan 18, 2006 5:17 pm
by RV4ker (RIP)
Posted: Wed Jan 18, 2006 5:31 pm
by Tumbleweed
Doing my first cross country, we took 1 hour 35 min from Secunda to Springs and 40 minutes to get back.
Beautifull sailing till the last 15 minutes which became such a 'gat stamp' I thought is was part of an initiation shake.
I suppose if tailwind does'nt exsist then the air can move pretty erratically sometimes.