Fogheavy

Fogheavy is a neologism used in weather discourse to describe an unusually dense and persistent fog event. It is not an official meteorological classification, but a descriptive label that emphasizes both intensity and duration. The term appears in regional reporting and online discussions rather than in formal climate documentation, and its thresholds can vary by context.

Definition and thresholds: Fogheavy refers to visibility typically under 200 meters, often much lower, accompanied by high liquid water content and a stable boundary layer. It tends to persist for several hours to days, especially when cold air sits over a moist surface and winds remain light. In practice, fogheavy may be reported during commuter delays or aviation advisories, even when standard fog labels would suffice.

Formation and drivers: Fogheavy arises from combinations of radiation fog and advection fog, and sometimes sea or lake fog when air mass moisture is high and surface cooling is strong. The defining feature is not only how little can be seen, but how long that poor visibility lasts, often through early morning and into daytime as conditions slowly improve.

Impacts and considerations: Dense fog events disrupt transport, increase accident risk, and raise energy use due to heating. They also affect outdoor work, photography, and emergency services. In risk communication, fogheavy may warrant enhanced alerts even if standard fog labels are not triggered.

Origin and usage: The term fogheavy blends fog with heavy, paralleling common language phrases. Its use is informal and regionally variable; it has no global standard definition and should be interpreted in context with local meteorological guidance.

Related topics include fog, dense fog, visibility, advection fog, and radiation fog.