There are several mechanisms that cause dynamic rising motion. Warm air advection in the low levels of the troposphere causes rising air. This is because warm air expands, creating a higher thickness, which in turn causes the air to rise. Positive Vorticity Advection causes the air to rise. The three terms that make up positive vorticity in the Northern Hemisphere include counterclockwise curvature, counterclockwise shear on a horizontal plane, and earth's counterclockwise Coriolis. Divergence and rising air occur in the right rear and left front quadrants of a jet streak. Any low level density boundary will lead to rising motion if convergence occurs along that low-level boundary. Low level boundaries include fronts, outflow boundaries, moisture gradients, and sea breeze fronts. Upslope flow forces the air to rise. Isentropic lifting, by way of warm air advection over a frontal boundary or a cold shallow dome of air, will cause the air to rise. Convergence in the low levels will cause the air to rise. The best examples are convergence along frontal boundaries and frictional convergence into low pressure. |