station model

Method of representing information collected by an observation station on a weather map using symbols and numbers.

air temperature

Sensation of heat or cold (°F) measured using an open-air thermometer shielded from direct sunlight.

wind direction

Wind direction is indicated by the position of the wind shaft.

present state of weather

Type of precipitation (present weather) noted at the moment of observation.

temperature of dew point

Temperature (°F) at which water vapor in the air begins to condense; it is used to calculate humidity in the air.

type of low cloud

Type of cloud observed between ground level and an altitude of 6,500 feet.

pressure change

Positive or negative value that corresponds to the difference between the pressure reading and sea-level pressure; it is expressed in inches of mercury.

barometric tendency

Variation in atmospheric pressure during the three hours preceding observation.

sky coverage

Proportion of the sky covered with cloud.

sea-level pressure

Reference pressure that corresponds to the pressure observed at sea level; it is expressed in inches of mercury.

station circle

Circle on a weather map that represents an observation station; displayed around the circle is the information collected by the station.

type of middle cloud

Type of cloud observed at altitudes between 6,500 and 20,000 feet.

type of high cloud

Type of cloud observed at altitudes higher than 20,000 feet.

wind speed

Wind speed is indicated by barbs and pennants whose values must be added.