Read Every Cloud

There I was nearing cloudbase. I had been running along a nice cloud street into the wind. It had been a long lonely day and now I had company... woohoo... Getting to the last cloud on the street already near cloudbase, I made a few turns and noticed something odd. This shadow wasn't drifting like the others.

The mountains were well upwind (maybe 20 miles). All day the clouds had been drifting like you would expect them to do on a thermal day. This one was different. It was wave influenced. I was able to climb the leading edge of the cloud in the smooth wave and made it home using the wave. The company that had joined me a few minutes before had decided the thermal was decreasing and left. We met again on the retrieve as I helped disassemble his glider from the field

We all have read wave from textbooks. Nice stable air coming down the backside of the mountain and bouncing back up again. Possibly a lenticular cloud maybe even with a rotor cloud underneath it. Remember lenticulars and rotor clouds are not going to drift with the wind. They are going to be stationary because it is being formed from the mountain.

Wave can form by a thermal that is pushing into an inversion layer, with a strong wind increase in the stable air, wave can form. This is very common in Australia and Ingo Renner was known for being significantly higher then most at the start. I had one day at JoeyGlide (Australian Junior Nationals), where I spent the entire first leg drifting downwind on-top of the thermal layer. This was great except I forgot how to thermal and took a bad line on the second leg.

These days the wave system is above the thermal layer and can be forecasted by a strong inversion and a strong change in winds in the stable layer. The stable air and wind would look similar to a mountain wave day forecast.

 

garret willat  Garret Willat holds a flight instructor rating with over 8000 hours in sailplanes. His parents have owned Sky Sailing Inc. since 1979. He started instructing the day after his 18th birthday. Since then, Garret has represented the US Junior team in 2003 and 2005. He graduated from Embry-Riddle with a bachelor's degree in Professional Aeronautics. Garret represented the US Open Class team in 2008 and 2010 and the Club Class team in 2014. Garret has won 3 US National Championships.