•The thermal wind is a vertical shear in the geostrophic
wind caused by a horizontal temperature
gradient. Its name is a misnomer, because the thermal wind is not actually a wind, but rather a wind gradient.
•The vertical shear (including direction and speed) of
geostrophic wind is related to the
horizontal variation of temperature.
•è The thermal wind equation is an extremely useful
diagnostic tool, which is often used to
check analyses of the observed wind and temperature fields for
consistency.
èIt can also be used to
estimate the mean horizontal temperature advection in a layer.
èThermal wind blows
parallel to the isotherms with the warm air to the right facing downstream in the Northern Hemisphere.