In meteorology, loosely used for any influence upon the direction of movement of an atmospheric disturbance exerted by another aspect of the state of the atmosphere. Thus, it might be said that a surface pressure system tends to be steered by isotherms, contour lines, streamlines aloft, warm-sector isobars, the orientation of a warm front, etc. Nearly always this principle is applied to the relationship between the velocity of a cyclone and the velocity of the basic flow in which it is embedded.