What Are The Criteria To Report Haze, Smoke Haze, And Fog In METAR?

Meteorologists use the term “haze” to describe phenomena that obscure visibility.  The term “smoke haze” is used to describe a similar situation that occurs when smoke from wildfires or industrial emissions settles out of the air. The term “fog” is used to describe a thick layer of clouds near ground level that reduces visibility. Fog is a natural phenomenon and not always harmful to human health, but it can be hazardous if the weather conditions are severe.

Fog can occur at any time of year, but it is most common in fall and winter.  Fog can develop suddenly and rapidly or gradually over a long period of time.  A fog bank is a large mass of fog that forms over an open body of water. Fog can be caused by many different weather phenomena, including:

• Water vapor condensing into droplets or liquid water

• Cool air rising through warmer air

• Mist from precipitation falling back to earth

• Water vapor rising through hot air

• Winds pushing warm air up over cooler air

• Cold fronts moving through warmer air

Criteria To Report Haze in METAR:

In meteorology, haze refers to a type of atmospheric aerosol that causes reduced visibility, leading to a hazy or foggy appearance in the air. Haze occurs when dust, smoke, and other dry particles, such as ash or pollen, become suspended in the air, reducing the clarity of the atmosphere. It is often caused by human activity, such as industrial pollution, transportation emissions, and wildfires. Haze can have a significant impact on air quality, making it difficult to breathe for people with respiratory problems. It can also impact weather patterns, as it reduces the amount of solar radiation that reaches the earth’s surface. Haze is often measured using instruments such as visibility sensors or particulate matter monitors, and is monitored by weather agencies to alert the public of potential health hazards.

Haze is reported in METAR when visibility is more than 1 km R.H (Relative humidity) is less than 49%.

Criteria To Report Smoke Haze in METAR:

Smoke haze is reported when visibility is more than 1 km and R.H (Relative humidity) is more than 49%

Criteria to Report Fog in METAR:

Fog is a collection of water droplets and smaller particles that are suspended in the air. Fog is most commonly created when warm air rises and cool air condenses. Fog can also form when moisture is added to air that is already humid.

The fog is created when the water evaporates from the surface of the earth, forming clouds, which are then lifted by the wind to form the fog. Fog is a mixture of water vapor and small droplets of water suspended in the atmosphere. Fog is a good example of a “cloud” without any precipitation (rain, snow, or sleet).

Fog is reported in METAR when visibility is less than 1 km and Relative humidity (R.H) is more than 90%.

Holds BS Degree in Electrical Engineering and MS Degree in Meteorology and currently working in the field of meteorology as an assistant weather forecaster. Love helping people know what the weather is doing. Researcher of the weather conditions and make forecasts for several different locations.

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