Damo said...I am more than happy to be proven wrong on this Steve but there is nothing in your link that i can see that is even relevant let alone backs up your argument that i am talking "nonsense"
I'm not saying that 30knots in the tropics is moving SLOWER than 30 knots in the arctic. What i am saying is that the amount of power that your kite can generate in 30 knots in the tropics is less than the amount of power your kite will generate in 30 knots in the arctic.
I'm not pretending to know everything on the subject so if someone can find something more relevant than some over complicated intellectual ramblings on wikipedia I'm happy to be corrected as this is something that has interested me for awhile now and as Steve says there is so much misinformation out there.
Here is another wikipedia link that i found to be more relevant
en.wikipedia.org/wiki/Density_altitude Damo, and everyone else. I'm not a physics professor, so have an "amateur" understanding of the principle, so I'll try and explain in my words.
Velocity of air is not dependent on the density of the air, put another way the speed that air is travelling at is what is measured by wind speed measuring instruments and temperature and density don't affect the measurement of impellor/propellor type instruments, which are commonly used to measure the wind, even by the BOM and CSIRO. So 30 knots somewhere = 30 knots anywhere. ( my words and understanding, not absolute fact, but I believe pretty close to it
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Warnings about wind in winter are about winter storms and squalls and the fact that is some areas winter winds are stronger.
Cars don't run better in colder temperatures, they will actually run worse, unless the air/fuel mixture has been adjusted to compensate for the extra density of the colder air, but that has nothing at all to do with wind and measuring the velocity of wind.
The pressure change in a balloon that is cooled down also has nothing to do with the velocity of wind, and has to do with a natural property of gases and fluids (most fluids?) - they expand when heated (become less dense) and contract when cooled (become more dense).
Less dense air moving at 30 knots VELOCITY, has the same VELOCITY as 30 knots of more dense air.
As for the work or energy that can be exchanged by less dense 30 knot wind versus more dense 30 knot wind, my understanding is that the difference is minimal - almost undetectable - by a person flying a kite.
The most important factor that affects us as kite flyers is the VELOCITY of the wind, not the density or temperature.
Maybe someone with a better understanding of the principles can explain what difference, if any, temp of measured moving air has on the power it can deliver to a kite, that moves at quite low speeds?
