Weather map

[Sarah]

A map or chart showing the principal meteorological elements ata given hour and over an extended region. Such maps usually show theheight of the barometer, the temperature of the air, the relativehumidity, the state of the weather, and the direction and velocity ofthe wind. Isobars and isotherms outline the general distribution oftemperature and pressure, while shaded areas indicate the sectionsover which rain has just fallen. Other lines inclose areas where thetemperature has fallen or risen markedly. In tabular form are shownchanges of pressure and of temperature, maximum and minimumtemperatures, and total rain for each weather station since the lastissue, usually 12 hours.