In weather terms, what does "FU" refer to?

"FU" in weather terminology specifically refers to smoke. This abbreviation is used in meteorological reports to denote smoke presence, which can be a significant factor in aviation and weather conditions. Smoke can arise from various sources, including wildfires or industrial activities, and can affect visibility and overall flight safety.

The presence of smoke in the atmosphere can lead to reduced visibility and potentially hazardous flying conditions, which is critical information for air traffic controllers and pilots. Understanding different weather phenomena and their abbreviations enables better preparation and response to various atmospheric conditions that might impact flight operations.