Kitesurfing Lessons – The Wind and Weather

Posted under Kitesurfing Lessons

By its very nature this section could have gone on forever but I’ve tried to break down the information to what’s important to you right now as someone who is looking at doing kitesurfing lessons and possibly (hopefully) practicing with a trainer kite. So we’ll look mainly at different wind effects which will alter the way your kite flies.

There are several types of wind effects we need to be aware of when flying a kite anywhere but these become especially pertinent for those of you flying kites in built up areas or around obstacles.

Gradient Wind:

The wind will get slower the closer to the earth it is, this is because as the wind passes over the earth (or sea) it generates friction, slowing it down, the more uneven the earth (or sea) surface the greater the effect of this friction and the higher the difference between the wind at ground level and the wind higher up in the atmosphere. This effect is called Gradient wind. The earth generally causes more friction than the sea which is why often on beaches with an onshore wind there is a line of ‘dodgy’ wind at the shore line as the wind hits the beach and slows down due to the increased friction. For us kiters this means that what we feel on our face will almost definitely not be the wind that our kite is feeling 25m up in the air.

Wind Shadow

A wind shadow is created by an obstacle in the path of the wind, which is why we huddle behind walls to shelter from the wind sometimes.  The wind however does not simply stop when it hits this obstacle but attempts to get around it any way it can.  That is it will go over, under or around it, this creates a patch behind the obstacle where the wind is very turbulent as it is coming from potentially several different directions at once.  The best way to envisage this is to imagine rapids in a river, when the water hits a rock you get white water around and behind the rock as the water tumbles over the top and around of it in a struggle to carry on moving downstream.  This is exactly what we would see if we could ‘see’ the wind. An obstacle will cast a shadow (disrupt the wind) up to 7 times its height down wind.

Updraft

An obstacle in the path of the wind will not only create a disruption downwind of it (a wind shadow) it will also create a disruption upwind of it.  Think back to our example of the rapids, not only do you see white water behind the rock but also infront of it this is caused as water that cannot get out of the way hits the obstacle and is reflected back into the path of the oncoming river causing disruption and forcing the water behind it upwards and over the top of the reflected water, thus creating updraft. This is an extremely important effect to know about and it is for this reason that we should not kitesurf too close to large cliffs or practice kite flying in-front of large obstacles. The upwind disruption is equal to 3 times the height of the obstacle.

The Venturi Effect

This is particularly pertinent to me here in Tarifa as this is the reason why its so bloody windy here! The Venturi effect states that when wind passes between two obstacles the wind speed will increase as it is forced through the gap.  So here at Tarifa we have the straights of Gibraltar and on either side we have mountains, the Riff Mountains in Morocco and Gibraltar on the Spanish side, wind coming from any direction is forced through this gap and accelerated out the other end giving Tarifa its famously consistent Levante and Poniente winds.

Got it?!

Don’t worry, your Instructor will take you much deeper into wind and weather during your kitesurfing lessons but with these basics you should at least be able to stay safe and recognise the different effects taking place in any one area

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