A ridge is the extension of an anticyclone visible as an anticyclonic curvature of isobars. It represents an axis of relatively higher pressure favouring sinking air (subsidence) and settled weather.
Heat ridges
In summer, upper-level ridges extending from North Africa over the Iberian Peninsula drive the most severe heat waves. Descending air compresses and warms, suppressing convection and trapping hot air beneath a "heat dome". It is the dynamic opposite of a trough.