What does the code GR represent in weather reports?

The code "GR" in weather reports specifically denotes hail, which is a type of solid precipitation that falls in the form of ice pellets. When interpreting weather reports, understanding the shorthand codes is essential for quickly assessing weather conditions, especially for aviation safety.

Hail is typically associated with thunderstorms and can vary in size, intensity, and duration. The presence of hail can significantly impact flight safety, as it can cause damage to aircraft during takeoff, landing, or flight. Recognizing "GR" alerts pilots and meteorologists to anticipate the possibility of this hazardous weather phenomenon.

In contrast, the other options correlate to different weather phenomena: blowing spray relates to water droplets in strong winds, partial fog indicates reduced visibility due to moisture or mist, and blowing sand refers to loose sand particles being lifted and transported by wind. Each of these has its own specific code and implications for weather reporting, but "GR" unequivocally refers to hail.