What indicator is used for wind direction in FD codes?

The indicator used for wind direction in FD codes is represented by "dd." In the context of meteorological reporting, "dd" specifically signifies the direction from which the wind is blowing, measured in degrees from true north. For example, a wind direction of 270 degrees indicates a west wind.

Understanding wind direction is crucial in aviation as it affects aircraft performance, navigation, and safety. Correctly interpreting this information helps pilots make informed decisions regarding takeoff and landing procedures, as well as en-route navigation.

In contrast, "ff" typically refers to wind speed, often expressed in knots; "tt" is used for temperature; and "rr" signifies the amount of precipitation in a specific period. Each of these indicators serves a specialized role in weather reporting.