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A trough is an elongated region of relatively low atmospheric pressure without a closed isobaric contour that would define it as a low pressure area. Since low pressure implies a low height on a pressure surface, troughs and ridges refer to features in an identical sense as those on a topographic map. Troughs may be at the surface, or aloft, at ...
Airflow around troughs and ridges in upper troposphere. Given the direction of the winds around an anticyclonic circulation and the fact that weather systems move from west to east: [2] ahead of an upper-ridge, the airflow that comes from the polar regions and brings cold air.
On its western side, the ridge is flanked by two back-arc basins, the Lau Basin and Havre Trough, that began opening at 6 Ma and 2 Ma respectively. Beyound the basins is the Lau-Colville Ridge. Together with these seafloor structures the ridge forms the eastward-migrating, 100 million year old Lau–Tonga–Havre–Kermadec arc/back-arc system ...
Shortwave troughs are a cause of lift, or forcing, which is required for the development of thunderstorms and convection.Convection is very prevalent around shortwave troughs because not only do they provide forcing, but they are also associated with systems that provide other ingredients for the formation of thunderstorms, such as instability, wind shear, and helicity.
To the south it is now thought seafloor spreading at the Havre Trough started about 5.5–5.0 million years ago in response to the rollback of the subducting Pacific Plate and terminated abruptly about 3.0–2.5 million years ago, perhaps explaining the long noted lack of a mid oceanic ridge structure but rather rift like subsidance. [16]
Using charts of mean 200-hectopascal circulation for July through August (located 9,200 metres (30,200 ft) above sea level) to locate the circumpolar troughs and ridges, trough lines extend over the eastern and central North Pacific and over the North Atlantic.
Ridge and furrow is an archaeological pattern of ridges (Medieval Latin: sliones) and troughs created by a system of ploughing used in Europe during the Middle Ages, typical of the open-field system. It is also known as rig (or rigg) and furrow, mostly in the North East of England and in Scotland. [1] [2] [3]
A plot of geopotential height for a single pressure level in the atmosphere shows the troughs and ridges (highs and lows) which are typically seen on upper air charts. The geopotential thickness between pressure levels – difference of the 850 hPa and 1000 hPa geopotential heights for example – is proportional to mean virtual temperature in ...