Thermals, Up & Downdrafts - Realism Update/ Airmass Simulation

I just re-watched the Jan 2021 Developer Q&A twitch and the discussion of thermals seems totally disconnected with what’s actually happening in the sim.

There is neglible thermal activity in the sim.

Thermals are not ridge lift - ridge lift in MSFS seems ok.

Thermals are not turbulence - turbulence in MSFS seems ok.

Thermals not appearing over seas and large bodies of water is not an issue - no-one tries to soar a glider over large expanses of water.

Thermals “limited to 1000 feet per minute” is a complete non-issue - that would be a GREAT thermal.

The issue is there are no thermals in MSFS. Every Cumulus cloud is there because air rose until it reached the condensation temperature. At that point it actually speeds up a bit (the condensing vapor releases a little energy). You can fly under hundreds of Cu’s in MSFS and will not encounter any thermals of any strength. In fact you can fly under a CuNim descending gently in dead calm, which in real life would be terrifying because you would be being lifted up into the cloud almost faster than you can dive out of it.

In case I haven’t made this clear enough, this is nothing to do with the sea, winter, mountains, ridge lift, or turbulence or a thermal strength cap or experienced RL glider pilots being too dumb to find the thermals in MSFS.

A simple test would be someone, somewhere, manages to actually gain height in a glider on a zero wind day (to eliminate the ridge lift), which RL glider pilots are pretty much certain to on any summers day almost anywhere in the world.

When we were first hunting for thermals, the turbulence caused by the excessive gust system (now dialled down) was enough to make you think MAYBE there was thermal activity but you couldn’t hook into it, but then we learned how to turn the gusts off and these phantom thermals disappeared. I’m guessing Asobo have been fooled by their own gusts to believe the thermal uplift is actually there, or maybe are assuming “thermal” means “updraft” so ridge lift counts as a thermal.

Note that ridge lift (wind blowing up a slope) works all the way down to near ground level (accepting the wind will slow down due to friction with the ground) i.e. you could theoretically ridge soar twanging the hillside trees with your wing. This might make landing on a hillside airstrip tricky but isn’t normally an issue on flat airfields.

Thermals cannot magically ascend vertically out of the earth - there’s a slower zone at the first few hundred feet where the warm air collects to form a narrower rising column of air which then rises several thousand feet.

Microbursts are a wacky extreme process of this operating in reverse. A large parcel of unstably cooled air descends rapidly until it smacks into the ground. This, thankfully, isn’t common like thermals, but can occur when there are large airmass temperature differentials (i.e. it’s “stormy”).

“Thermals limited to 1,000 feet per minute” - yeah sure.

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