True or Magnetic???

[ffejsmada]

When the BOM say SE wind or NW wind etc, is that given to us in the magnetic reading or the true reading of the compass?

I know it's only a few degrees out, but just curious as that few degrees could mean blown out or sheltered spots in rivers, creeks etc.

Cheers Jeff.

[Foxy4]

Now thats a very interesting point.

[oldboot]

I dont think wind is that precise.

they usualy say..... N to NNW winds or someting similar..... its not like they are giving a bearing.


cheers

[Ian1]

Wind direction is given in true. Subtract 10 degrees for magnetic. For example wind from the east will be 080 degrees magnetic.

Cheers

Ian

[rockfisho]

Hi jeff


Wind spirals out of the high pressure systems and into the low pressure systems, the direction constantly changes as there are slight pressure fluctuations in the atmosphere.
As you can gather from this, the direction given is only really an approximate.

cheers

Owen

[tigermullet]

True for forecasts. Magnetic for actual reports.

[theoldlegend]

I wouldn't have thought it would have been a big ticket item.

But then again, who knows?


TOL

[Murph77]

Wind direction is given in true. Subtract 10 degrees for magnetic. For example wind from the east will be 080 degrees magnetic.

Cheers

Ian

Remember that the magnetic variation changes with location. It's true that you subtract 10 degrees here in SE QLD but, for example, in Darwin the magnetic variation is virtually nil i.e. true = magnetic, and in WA the variation is west which means that mag is greater than true.
Basic rule - Variation EAST = magnetic LEAST, variation WEST = magnetic BEST