from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun physics, meteorology a widespread body of air, the properties of which can be identified as: (a) having been established while that air was situated over a particular region of the earth's surface (airmass source region) and (b) undergoing specific modifications while in transit away from the source region. An air mass is often defined as a widespread body of air that is approximately homogeneous in its horizontal extent, particularly with reference to temperature and moisture distribution; in addition, the vertical temperature and moisture variations are approximately the same over its horizontal extent.


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  • The top of the “anvil” that you see at the top of a thunderstorm is actually the level at which buoyant parcels reach equilibrium with the surrounding airmass, which is generally isothermal (in the vertical) at that height (i.e., the tropopause).

    USCCSP: Temperature Trends in the Lower Atmosphere « Climate Audit

  • Tomorrow Wednesday: Sunshine is abundant and while the airmass is still cold, high temperatures should climb into the low-to-mid 40s.

    PM Update: Clear and chilly

  • In that pattern, Arctic airmass after Arctic airmass originating from northern Canada dove southeast, driving windy cold fronts through the region.

    High wind watch for the region yet again

  • Near average temperatures appear to be on tap, in the low 50s Monday up to, perhaps, upper 50s Tuesday should the airmass modify over our region.

    Forecast: Fine Friday before wet weekend

  • Any of a number of subtle changes to the airmass and its trajectory over the ocean could make dramatic differences to the eventual outcome.

    Snow in San Francisco? Could happen late Friday

  • Jeff Masters at Weather Underground explains the cause of the storm: A potent jet stream with strong winds will dive southwards over the central U.S. today, allowing a cold Arctic airmass to spill southwards out of Canada.

    Snow storm to bury Midwest, New England

  • A rather warm and dry airmass to the west builds over the region for Wednesday and Thursday.

    Forecast: Showers to dissolve, dry weather nears

  • However, the dry airmass does promote clear skies and hence increased insolation which allows more radiant energy to reach and heat the ground and elevate the surface air temperatures by conduction and the lowest levels in the atmosphere by convection.

    Unthreaded #21 « Climate Audit

  • But, if the airmass at the same temperatures becomes saturated enough to produce fog condensed water droplets the rate of diminution of the snow cover increases dramatically.

    Unthreaded #21 « Climate Audit

  • So higher desert temperatures have a lot to do with where the airmass originated and the effect of an intervening mountain range.

    Unthreaded #21 « Climate Audit


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