OW glossary
Dwye:
Also spelled dwy, dwey, dwigh, dwoi, dwoy
Eddy, gust, flurry; squall; brief shower or storm ... of rain, hail or snow.
Dictionary of Newfoundland English [AvastMH]
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I have a nfld term for snow squalls. People from Fogo call it snow dwye.
https://twitter.com/RickG709/status/164102179811102721
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https://i.imgur.com/uDUpnBH.png (from the New York Times archives.)
Fata Morgana:
A complex form of superior mirage.
https://en.wikipedia.org/wiki/Fata_Morgana_%28mirage%29
Fine:
Fine weather is sometimes used in whaling ships recording that day's weather and is a combination of good sailing winds, clear skies and calm seas.
[Kevin]
Mirage:
A superior mirage occurs when the air below the line of sight is colder than the air above it.
This unusual arrangement is called a temperature inversion, since warm air above cold air is the opposite of the normal temperature gradient of the atmosphere. Passing through the temperature inversion, the light rays are bent down, and so the image appears above the true object, hence the name superior.
Superior mirages are in general less common than inferior mirages, but, when they do occur, they tend to be more stable, as cold air has no tendency to move up and warm air has no tendency to move down.
Superior mirages are quite common in polar regions, especially over large sheets of ice that have a uniform low temperature.
https://en.wikipedia.org/wiki/Mirage#Superior_mirage
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https://www.coolantarctica.com/gallery/ ... ather4.php
philip.brohan wrote:Tue Jan 24, 2012 10:56 am
Some aspects of the weather can vary over short distances. We've all seen rain falling a short distance away but not on us, and any dingy sailor will know about local fluctuations in the wind - on the other hand air pressure doesn't vary over short distances (except in tornados).
So when we see two ships together (usually in a port) IF they had perfect instruments they would agree about air pressure and cloud fraction, they might disagree about the wind and the rain, temperature is a bit more difficult.
In complex environments temperature may vary noticeably over a short distance - it will be hotter over the (black) tarmac of a road than the (green) grass of a verge, for instance; look out of your window on a cold morning and you'll often see ground frost in some places and not others. As a weather-man, I want the temperature away from all such local complications, and (land) weather stations are deliberately placed in boring environments (level, open fields, away from trees etc.) to get rid of these effects.
Very few ships have a large area of open grassland on board for us to site their thermometers in. They do try to site the thermometers in places where the local temperature perturbation from the ship itself is small, but each ship carries its own microclimate, and that microclimate varies according to the angle between the ship structure and the sun. So even when at sea there will be differences between air temperatures recorded by different ships as they meet, and in port there may be additional complicating factors from the different adjacent land features. (You should see less difference in seawater temperatures (which have different issues) and in temperatures recorded at night (when the local effects are much smaller)).
On top of this - ships don't have perfect instruments and humans are not perfectly reliable in reading and recording the instruments they do have.
So don't expect perfect agreement, even between co-located observations. But don't think the complications make the observations useless either - one of the main tasks of my colleagues and myself is to disentangle these complications, and comparing observations from co-located ships is a great help in doing this. I don't have any results from our ships to show you today, but I enclose something I
prepared earlier - this shows pressures observed in Portsmouth by a batch of later RN ships - there are systematic differences between the barometers, probably from imperfect calibration.
Please post questions and suggestions for additions or changes in
Weather, sea, and ice (past, present, or future -- on Earth or elsewhere): discussion.
