Chiefly shows prevailing winds at different elevations; also shows sea temperature, fog, currents, magnetic variation, airplane routes, and steamer routes.

"The upper air data on the face of this chart were collected and furnished by the U.S. Weather Bureau, and correlated by the U.S. Hydrographic Office."--Upper right margin.

Includes 2 insets showing barometric pressure, air temperature, and gales.

"No. 1400a"--Upper left and lower right margins.