I’m not even talking about the transition, when I’m at an airport and look at the real world METAR I would expect:
- The ATIS to exactly match that METAR.
- Clouds not to be on the ground.
- Visibility to more or less match.
- Correct QNH, temperature and dewpoint.
- No mist or haze if the real world visibility is great.
I want to clear up one thing though, I don’t believe we are talking about haze in this thread, you can rarely see haze from ground level, usually it can be seen obscuring the horizon when flying higher. The definition of haze:
“A term you might also hear mentioned is haze. This is a slightly different phenomenon which is a suspension of extremely small, dry particles in the air, not water droplets. These particles are invisible to the naked eye, but sufficient to give the air an opalescent appearance.”
What we are actually discussing here is fog or mist, which is caused by a high relative humidity and subsequent condensation of moisture in the air.
Fog:
“Fog is defined as ‘obscurity in the surface layers of the atmosphere, which is caused by a suspension of water droplets’.”
”By international agreement (particularly for aviation purposes) fog is the name given to resulting visibility less than 1 km. However, in forecasts for the public, this generally refers to visibility less than 180 m.”
Mist:
“Mist is defined as ‘when there is such obscurity and the associated visibility is equal to or exceeds 1000 m.’ Like fog, mist is still the result of the suspension of water droplets, but simply at a lower density.”
“Mist typically is quicker to dissipate and can rapidly disappear with even slight winds, it’s also what you see when you can see your breath on a cold day.“
The majority of pictures I have seen in this thread so far is mist, not haze. Regarding mist and haze, I’m wondering where they get this info from. The METAR visibility only goes to 9999 (10 km or more), above they either take it from another source or some formula using the temp / dewpoint split.