Large scale

From Glossary of Meteorology

large scale

In meteorology, a scale in which the curvature of the earth is not negligible.

This is the scale of the high tropospheric long-wave patterns, with four or five waves around the hemisphere in middle latitudes. These waves are within the province of both the general circulation and synoptic meteorology, but the terminology should distinguish this scale from that of the migratory high and low pressure systems of the lower troposphere. Rossby waves and other long barotropic waves are large-scale disturbances.
See cyclonic scale.