We can now see thermals!

So, I've been pretty inactive here lately. Haven't had much to write about that was all that new and exciting.  Ran short of money to do my own thing and my health hasn't been that good leaving me with little energy to write. But lots of time for scouring the net for interesting new tech.  I keep up the conversation at Flapping Wings Forum but even that's been quiet.

So it was really exciting to finally see something that made me sit up and grin big.  As a soaring pilot, I've thought about the problem of finding lift when it is invisible.  You can guess where it might be, ridge lift is on the windward side of a ridge, hence the name.  Thermal lift however may start out associated with a dark field or parking lot but it rises and drifts in unpredictable ways.  Unless you can spot a bird, other glider or trash sucked up in the thermal, the only way you have to find them is just luck.

Thermals can be huge and powerful or light and small, but a good pilot can use them as free fuel, if he can find them.  I have stood on the mountain so many times and watched people dive off in a hit or miss attempt to find a thermal before they find the ground.  Some will get lucky and "get up" while others fly right by and "go down".  A lot of it is experience in knowing where to look.  Smart pilots watch what is happening and mark the best spots before launch by seeing what the others do.

It's a good feeling to get off and hook one, be climbing out while everyone else "hits the ground".  Not so great to miss it and have to break down in the hot midday sun.  Of course aero-towing has changed a lot of that for the flat land fliers.  The tug pilot usually tries to drop you off in your first thermal and you start with a couple of grand to work with, but still after that you're on your own.

Over the years I though hard about how to see thermals.  I've imagined wearing special goggles that overlay the view in front of you with indicators of rising and sinking air.  I've had hints but never really knew enough to imagine how it could be done.  One thing I know is that air of different temperatures transmits light differently.  Just like light going from air to water bends it so that a straight stick in water looks bent, where air of different temperatures meet, the light is bent there too.

We see this all the time but either don't notice it or it does not matter except to give another indication of how hot it is.  The shimmer effect and the mirage are the result of air being heated by the sun.  It is concentrated near the surface of a parking lot or the hood of a car.  Sometimes you see it over a radiator or heater and it can be seen in the shadow of the heat rising from a candle.  But the effect is only visible to our eyes when the temperature difference is great. 

Even a powerful thermal rising a thousand feet per minute or greater is the result of temperature differences that are too small to see let alone feel.  We can't see them. Until now.

What we are looking for is not to see the air itself, what we want to see is the effect,  we want to see how the stick is bent at the water line.  We want to see how the background is "shimmered" by the distortion of the difference in refractive index of the air. 

But there are lots of other things that move slightly or change in other ways so tiny that we can't visually pick it up.  The video at the bottom of the page talks about such things and explains them so I don't need to.  It is the work of MIT scientists.

In a nut shell, they have figured out how to take video imaging and pixel by pixel, amplify small changes.  Do watch it.  It has nothing to do with flying at all and the only thing in the article that made me realize what they had was this image:

That is a picture of a thermal. It's just one tiny shot from the video.  Most of the rest is showing how they can take video of a persons face and show the tiny movements and color changes caused the person's pulse.  This will have valuable uses in medicine for sure.

But now I can imagine a viewer that I can use on the hill to view the valley and watch in real time how the thermals are forming and moving out in front.  I can see using a radio to direct pilots right to them.  And in the future, I can see those thermal goggles become a reality.

Here is the video:

 

Comments

[Daedelus]

1.

My friend Clark set up a GoPro on the bluff today and shot a bunch of video of the valley and some gliders thermaling out in front. Got some good stuff and I'm sending it to the guys at MIT who are working on the visualization project. They are going to see what they can do with it. Any luck and we'll have some video of actual thermals to look at.