/hawr"frawst', -frost', hohr"-/, n.
frost (def. 2).
[1250-1300; ME hor-frost. See HOAR, FROST]

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      deposit of ice crystals on objects exposed to the free air, such as grass blades, tree branches, or leaves. It is formed by direct condensation of water vapour to ice at temperatures below freezing and occurs when air is brought to its frost point by cooling. Hoarfrost is formed by a process analogous to that by which dew is formed on similar objects, except that, in the case of dew, the saturation point of the air mass is above freezing. The occurrence of temperatures below 0° C (32° F) is not enough to guarantee the formation of hoarfrost. Additionally, the air must be initially damp enough so that when cooled it reaches saturation, and any additional cooling will cause condensation to occur. In the absence of sufficient moisture, hoarfrost does not form, but the water in the tissues of plants may freeze, producing the condition known as black frost.

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Universalium. 2010.

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Look at other dictionaries:

  • Hoarfrost — Hoar frost , n. The white particles formed by the congelation of dew; white frost. [Written also {horefrost}. See {Hoar}, a.] [1913 Webster] He scattereth the hoarfrost like ashes. Ps. cxlvii. 16. [1913 Webster] …   The Collaborative International Dictionary of English

  • hoarfrost — c.1300, hore forst; see HOAR (Cf. hoar) + FROST (Cf. frost) (n.) …   Etymology dictionary

  • hoarfrost — [hôr′frôst΄] n. [ME horfrost: see HOAR & FROST] FROST (sense 3) …   English World dictionary

  • hoarfrost — Frost Frost (fr[o^]st; 115), n. [OE. frost, forst, AS. forst, frost. fr. fre[ o]san to freeze; akin to D. varst, G., OHG., Icel., Dan., & Sw. frost. [root]18. See {Freeze}, v. i.] 1. The act of freezing; applied chiefly to the congelation of… …   The Collaborative International Dictionary of English

  • hoarfrost — hoar|frost [ˈho:frɔst US ˈho:rfro:st] n [U] formal [Date: 1200 1300; Origin: hoar gray, white (11 20 centuries) (from Old English har) + frost] a thin layer of ice that forms on objects outside when it is very cold = ↑frost ▪ A light hoarfrost… …   Dictionary of contemporary English

  • hoarfrost — šerkšnas statusas T sritis fizika atitikmenys: angl. hoar; hoarfrost; rime vok. Rauhreif, m rus. иней, m pranc. givre, m …   Fizikos terminų žodynas

  • hoarfrost — šerkšnas statusas T sritis ekologija ir aplinkotyra apibrėžtis Ledo nuogulos, žiemą nusėdančios iš oro ant medžių šakų, laidų ir kitų smailių paviršių. Kristalinis šerkšnas susidaro vandens garams kondensuojantis priešvėjinėje objektų pusėje, kai …   Ekologijos terminų aiškinamasis žodynas

  • hoarfrost — noun Date: 14th century frost 1b …   New Collegiate Dictionary

  • hoarfrost — noun Dew drops which have undergone deposition and frozen into ice crystals to form a white deposit on an exposed surface, when the air is cold and moist. See Also: hoar …   Wiktionary

  • hoarfrost — sb. Fragm. Sci. 232 …   Oldest English Words

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