Lines of constant pressure are called isobars. The Thermal Wind - note the following descriptions of atmospheric motion are for small scales. Coriolis forces are ignored. In basic terms, heating gradients produce wind through the thermal wind . Pressure decreases with height in proportion to the mass of the column.
Warmer air is less dense than cooler air.
So pressure will decrease with height more slowly over warm land than over cold land. If the pressure is fixed at the surface, a pressure gradient will emerge at upper levels. This basic physics is relevant to motions of several scales. If Coriolis forces are present, however, the resulting motion is along isobars, not across them. Below, we mention types of thermal winds.