What does "HZ" mean on METAR?

In METAR reports, "HZ" specifically stands for "haze." This term is used to indicate the presence of fine particulate matter in the air that reduces visibility, typically occurring in conditions where humidity is moderately high, such as during the late afternoon or evening hours following a hot day. Haze doesn't significantly restrict visibility as fog does, but it can still reduce visibility to less than 6 statute miles.

The other options signify different weather phenomena. Fog, for instance, is represented by the abbreviation "FG" and refers to a thick cloud of tiny water droplets suspended in the air that drastically reduces visibility to less than 5/8 mile. Dust storms, indicated by "DU," consist of strong winds lifting dust into the air, which can also impair visibility, while "IC" represents ice crystals in the atmosphere, commonly visible as sparkling particles when sunlight hits them at certain angles. Understanding these abbreviations is crucial for interpreting METAR reports effectively, especially for flight planning and safety.