The T button enables the turbulence display which uses different measures of vertical wind shear to highlight areas of potential turbulence. This display originated from the Aviation Weather Center.
LN(RICHARDSON NUMBER) trace (center) in violet with values approaching -2 at level of strong vertical wind shear. WIND SHEAR TKE PRODUCTION trace (left) in light pink with values approaching 10 kilojoules/sec at level of strong vertical wind shear.
In the turbulence displays the data are plotted as follows:
LN (RICHARDSON NUMBER) (unitless, violet, top x-axis) - the natural log of the Richardson number. Values approaching 0 or less are favorable for turbulence of slight magnitude or greater according to the AWC. The AWC advises there are no set thresholds, and numbers as high as 1.8 can imply a risk of turbulence.
Wind Shear Tubulent Kinetic Entergy (TKE) Production (x 1E3 joules/sec, peach, bottom x-axis) - another calculation of vertical wind shear that is computed using the following formula:
0.54 x (layer thickness) x (vertical wind shear)**2
where the vertical wind shear is the change in wind shear vector with height.