is there any difference between kiting 20kt wind on a cold 5 Celius day wind vs 20 kt wind on a hot 35 Celius day
besides wearing a wetsuit
colder winds packs denser air and therefore is more powerful. www.engineeringtoolbox.com/wind-power-d_1214.html
Almost the same power in a 20 knots hot day (30 c. +) sea breeze compared to 15-17 knots of cold winter wind.
When kite companies state that a 12m kite is suitable from 12 knots. I wonder what temperature this is based on?
They base it on the Beaufurt Index. That index is the same no matter what temperature as knots is knots in any climate.
All other factors being equal the difference in force applied to the kite is 10.8% less on the 35 deg C day compared to the 5 Deg C day.
However the reality is that the cold frontal driven wind of wind packs a meaner punch because it is usually more gusty. On a 20 knot day it may gust 25+ knots.
A seabrease driven summer brease is more likely to be closer to a constant 20 knots.
In the formula to calculate force is 1/2 density(of the wind) x velocity (wind speed) squared.
Any variation in the wind speed has a far greater impact in the to the force applied to the kite.
Whats more changes in temperature affect the denisty of the air. However when we calculate the air denisty using the ideal gas law we use temperature in Kelvin not Deg C. Kelvin starts at -273 Deg C.
So.... To input the 5 Deg into the formula its 273+5. To input 35 deg into the formula its 273+35....... All of a sudden we have only really had a marginal change in temp and therefore very little change to the density of the wind over 30 deg temp change.
Confused?
There is a very obvious noticeable difference in the 'push' of wind as result of air temp. Up in Cairns I would ride 12m pretty much all the time. On the same wind strength, say 18knts on the Sunny Coast I would ride a 10m.
I noticed this difference when I kited at Yeppoon as well.
So in short- yep there is a difference and you will notice it.
sometimes we get warm ambient temp days with very cold southerly winds and they really pack a punch like nothing else. 32 knots in that is different to 32 knots in Maui.
Colder air is more dense and therefore less of it is needed. In SE QLD I generally fly a 10m in 12-20 knt SE, but in a N I need 16-20 knts. I first wondered about this when I started kiting and a pilot told me that when they take off into a hotter N wind, they have to allow for it and increase speed and length of run up.
Though it's been noted here that location does effect this. When we get Northerlies, they are generally more consistent and less gusty that Southerlies.
Select to expand quotegokid said...
[br]is there any difference between kiting 20kt wind on a cold 5 Celius day wind vs 20 kt wind on a hot 35 Celius day
besides wearing a wetsuit
About 3 inches
Select to expand quotecauncy said..gokid said...
is there any difference between kiting 20kt wind on a cold 5 Celius day wind vs 20 kt wind on a hot 35 Celius day
besides wearing a wetsuit
About 3 inches
Select to expand quotefingerbone said..
Defiantly...15 knotts Sydney = 20 knotts Cairns
You mean the other way around.
Don't get us from the top end started on this topic ! We are the experts on skinny wind vs heavy wind.
If 15 kts is the measure , for me (83 kgs) 17 m and nugget , the same wind in Southern South Oz 10-12 m and 5'10" sb.
Also, for the same location in Southern South oz, big difference between north wind from the hot centre and wind from the south.
Select to expand quoteKazan said..fingerbone said..
Defiantly...15 knotts Sydney = 20 knotts Cairns
You mean the other way around.
Got the feeling he may be defiant about this
Select to expand quoteRails said..Kazan said..fingerbone said..
Defiantly...15 knotts Sydney = 20 knotts Cairns
You mean the other way around.
Got the feeling he may be defiant about this
I think thats right
