Crossisobaric

Crossisobaric refers to a concept in atmospheric science and meteorology that describes the movement of air across surfaces of constant pressure. Isobaric surfaces are defined as regions in the atmosphere where the pressure is the same. While we often think of air moving parallel to isobars due to the geostrophic force, crossisobaric flow indicates motion that is not strictly parallel but rather has a component perpendicular to these pressure surfaces.

This perpendicular component arises primarily due to friction, particularly near the Earth's surface, and also due to diabatic processes such as heating or cooling, and adiabatic processes like condensation or evaporation. Friction slows the wind, allowing pressure gradient forces to push air across isobars towards lower pressure. Similarly, differential heating can create pressure gradients that induce crossisobaric flow. In the upper atmosphere, where friction is negligible, crossisobaric flow is less common and typically associated with strong vertical motions and complex weather systems. Understanding crossisobaric flow is crucial for accurate weather forecasting and for studying atmospheric circulation patterns.