This plate illustrates typical weather situations by means of four surface weather maps: for February 18th, 1954; April 19th, 1955; July 3rd, 1955; and October 12th, 1954. All maps are based on data of 1:30 p.m. Eastern Standard Time for the afore-mentioned dates. There are two small inset maps: one shows air masses and the mean position of fronts in winter, the other shows the same concepts for summer.