Apparent wind vs True wind


Apparent wind and True Wind are terms that I heard a lot about when I was first learning to sail. I thought there was just wind, but I quickly found out that there are several terms for wind. These two particular terms are related to each other, so I thought I would talk to you more about them today and hopefully you will fully understand why Apparent wind vs True wind is important.

Running ManApparent wind is the wind that you feel when you are moving. Pretty simple, right? Okay, so maybe a better explanation is in order. Think of it this way, on a windless day you decide to go jogging. As you are jogging down the street, you feel the wind in you hair and the wind against you skin. If you stop, you feel nothing. The wind that you felt while jogging is the apparent wind. You are actually moving through the wind and creating what feels like a breeze.

That example seems pretty simple, but what if it is not a windless day? This time when you are standing still, there is a 5 mph wind blowing directly towards you. If you were to ride a skateboard into the wind, you would feel an even stronger wind. If you could ride your skateboard 5 mph, you would feel and apparent wind of 10 mph. 5 mph that you are going on the skateboard and 5 mph for the wind blowing at you.

10 MPH Apparent Wind

 

So what happens when you are going “with” the direction of the wind? If the wind was still blowing 5 mph and you rode your skateboard, with the wind on your back, and you were going 5 mph, then you would feel no wind at all. You would be going the exact same speed as the wind, so you would feel nothing. In reality, you would probably feel some wind because the speed of the wind and your skateboard would vary, but you get the idea.

0 MPH Apparent Wind

 

Now, on to true wind. True wind is pretty simple, it is the speed of the wind when you are standing still. So if the wind is blowing in your face at 5 mph and you are not moving, then that is the true wind. This is what you hear on the weather when they talk about the wind speed, it is the true wind.

For sailing the apparent wind is important because it is the wind that is acting on the sails as you move forward. Apparent wind can be a little deceiving because the wind that you feel on your face and the wind that is acting on your sails is not always coming from the direction that it feels like. Sailors use wind vanes at the top of the mast to help them visualize the direction of the wind that is acting on the sails.

These definitions are the basics of apparent wind vs true wind.

Want to add to what I have above or see something that did not make sense? Please leave a comment below.

Corbett

 

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