What really causes daytime heating turbulence
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What really causes daytime heating turbulence
With all those bumps, it must be the rising air currents. Not according to this guy....
"The heating of the day causes convective thermals to rise—but the turbulence is not typically caused by the rising thermals alone. It is the interaction between the thermals and the prevailing winds aloft that really make the bumps.
These thermals act as obstructions to the normal air flow similar to mountainous terrain. The prevailing wind must deviate around the convective thermals resulting in turbulent eddies. These turbulent eddies are then carried downwind some distance before dissipating. The turbulent eddies are what we feel as bumps. Therefore, the intensity of the turbulence is related to the intensity of the thermals and the wind velocity."
Do you believe him?
"The heating of the day causes convective thermals to rise—but the turbulence is not typically caused by the rising thermals alone. It is the interaction between the thermals and the prevailing winds aloft that really make the bumps.
These thermals act as obstructions to the normal air flow similar to mountainous terrain. The prevailing wind must deviate around the convective thermals resulting in turbulent eddies. These turbulent eddies are then carried downwind some distance before dissipating. The turbulent eddies are what we feel as bumps. Therefore, the intensity of the turbulence is related to the intensity of the thermals and the wind velocity."
Do you believe him?
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Hot air will be blown away by wind. With certain wind (and convection) speeds thermal convection eddies may be blown downwind, creating a series of convective "bubbles" from a single thermal source.
I think there is an element of truth to this as after 5,000+hrs gliding I sometimes seem to be able to detect the presence/whereabouts of a thermal by associated turbulence; can’t really tell you how I do it 
. The roughest days are often those with lower lapse rates (more stable) as the thermals tend to be narrower with more defined shears on the edges, as entrained air does not have natural buoyancy. Same thing happens with sinking air.
I wouldn’t say that much of the turbulence associated with convective conditions is due to the above theory as it can be pretty bad on days with no vertical shear (or wind).
. The roughest days are often those with lower lapse rates (more stable) as the thermals tend to be narrower with more defined shears on the edges, as entrained air does not have natural buoyancy. Same thing happens with sinking air.I wouldn’t say that much of the turbulence associated with convective conditions is due to the above theory as it can be pretty bad on days with no vertical shear (or wind).
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It’s a slightly clumsy way of referencing the Richardson number of a flow (Wikipedia)
the complication being that there’s shear between a rising thermal and the environment, so it’s a bit chicken and egg.
the complication being that there’s shear between a rising thermal and the environment, so it’s a bit chicken and egg.
