HOME

TheInfoList




Frost is a thin layer of
ice Ice is water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of , eve ...

ice
on a
solid Solid is one of the four fundamental states of matter (the others being liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied ...

solid
surface, which forms from
water vapor (99.9839 °C) , - , Boiling point The boiling point of a substance is the temperature at which the vapor pressure 280px, The ''pistol test tube'' experiment. The tube contains alcohol and is closed with a piece of cork. By heating th ...
in an above-
freezing Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid o ...

freezing
atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

atmosphere
coming in contact with a solid surface whose temperature is below freezing, and resulting in a
phase changePhase change may refer to: * Phase transition, the transformation from one thermodynamic state to another. * Phase-change memory, a type of random-access memory. * Phase change (waves), concerning the physics of waves. {{disambiguation ...
from water vapor (a
gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space ...

gas
) to
ice Ice is water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of , eve ...

ice
(a solid) as the water vapor reaches the freezing point. In
temperate climate In geography Geography (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its populati ...
s, it most commonly appears on surfaces near the ground as fragile white
crystals A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...

crystals
; in cold climates, it occurs in a greater variety of forms. The propagation of crystal formation occurs by the process of
nucleation Nucleation is the first step in the formation of either a new or a new structure via or . Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organized structure appear ...

nucleation
. The
ice crystals Ice crystals Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust Diamond dust is a ground-level cloud composed of tiny ice c ...

ice crystals
of frost form as the result of
fractal In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers (arithmetic and number theory), formulas and related structures (algebra), shapes and spaces in which they are contained (geometry), and quantities a ...

fractal
process development. The depth of frost crystals varies depending on the amount of time they have been accumulating, and the concentration of the water vapor (
humidity Humidity is the concentration of water vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapo ...

humidity
). Frost crystals may be invisible (black), clear (
translucent In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions are ...
), or white; if a mass of frost crystals scatters light in all directions, the coating of frost appears white. Types of frost include crystalline frost (
hoar frost Frost is a thin layer of ice on a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic e ...
or radiation frost) from
deposition Deposition may refer to: * Deposition (law), taking testimony outside of court * List of deposed politicians, Deposition (politics), the removal of a person of authority from political power * Deposition (university), a widespread initiation ritual ...
of water vapor from air of low humidity,
white frost White is the lightness, lightest color and is achromatic (having no hue). It is the color of fresh snow, chalk and milk, and is the opposite of black. White objects fully diffuse reflection, reflect and scattering, scatter all the visible spec ...
in humid conditions,
window frost Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase transition, phase change from wat ...
on glass surfaces,
advection frost Frost is a thin layer of ice Ice is into a state. Depending on the presence of such as particles of soil or bubbles of air, it can appear transparent or a more or less bluish-white color. In the , ice is abundant and occurs natural ...
from cold wind over cold surfaces,
black frost Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase transition, phase change from wat ...
without visible ice at low temperatures and very low humidity, and
rime Rime may refer to: *Rime ice Rime ice forms when supercooled water liquid droplets freeze onto surfaces. Meteorology, Meteorologists distinguish between three basic types of ice forming on vertical and horizontal surfaces by deposition of superco ...
under
supercooled Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric process, isoc ...
wet conditions. Plants that have evolved in warmer climates suffer damage when the temperature falls low enough to freeze the water in the
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison cell, a room used to hold peopl ...
that make up the plant
tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubitata'', a species of geometer mot ...
. The tissue damage resulting from this process is known as "frost damage".
Farmer A farmer is a person engaged in agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exe ...

Farmer
s in those regions where frost damage is known to affect their crops often invest in substantial means to protect their crops from such damage.


Formation

If a solid surface is chilled below the
dew point Warmer air can hold more moisture than colder air. The dew point is the temperature to which air must be cooled to become saturated with water vapor. It is assumed that air pressure and water content is constant. When cooled further, the air ...
of the surrounding humid air, and the surface itself is colder than freezing, ice will form on it. If the water deposits as a liquid that then freezes, it forms a coating that may look glassy, opaque, or crystalline, depending on its type. Depending on context, that process also may be called
atmospheric icing 300px, The effect of atmospheric icing on a tree in the Black Forest of Germany. Atmospheric icing occurs in the atmosphere when water droplets freezing, freeze on objects they come in contact with. Icing conditions can be particularly dangerous to ...
. The ice it produces differs in some ways from crystalline frost, which consists of spicules of ice that typically project from the solid surface on which they grow. The main difference between the ice coatings and frost spicules arises because the crystalline spicules grow directly from desublimation of water vapour from air, and desublimation is not a factor in icing of freezing surfaces. For desublimation to proceed, the surface must be below the frost point of the air, meaning that it is sufficiently cold for ice to form without passing through the
liquid phase A liquid is a nearly Compressibility, incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of State of matter#The four fundamental states, the four f ...

liquid phase
. The air must be humid, but not sufficiently humid to permit the condensation of liquid water, or icing will result instead of desublimation. The size of the crystals depends largely on the temperature, the amount of
water vapor (99.9839 °C) , - , Boiling point The boiling point of a substance is the temperature at which the vapor pressure 280px, The ''pistol test tube'' experiment. The tube contains alcohol and is closed with a piece of cork. By heating th ...
available, and how long they have been growing undisturbed. As a rule, except in conditions where supercooled droplets are present in the air, frost will form only if the deposition surface is colder than the surrounding air. For instance, frost may be observed around cracks in cold wooden sidewalks when humid air escapes from the warmer ground beneath. Other objects on which frost commonly forms are those with low
specific heat In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quant ...
or high thermal emissivity, such as blackened metals, hence the accumulation of frost on the heads of rusty nails. The apparently erratic occurrence of frost in adjacent localities is due partly to differences of elevation, the lower areas becoming colder on calm nights. Where static air settles above an area of ground in the absence of wind, the absorptivity and specific heat of the ground strongly influence the temperature that the trapped air attains.


Types


Hoar frost

Hoar frost, also hoarfrost, radiation frost, or pruina, refers to white ice crystals deposited on the ground or loosely attached to exposed objects, such as wires or leaves. They form on cold, clear nights when conditions are such that heat radiates out to the open air faster than it can be replaced from nearby sources, such as wind or warm objects. Under suitable circumstances, objects cool to below the frost point of the surrounding air, well below the freezing point of water. Such freezing may be promoted by effects such as flood frost or frost pocket. These occur when ground-level radiation losses cool air until it flows downhill and accumulates in pockets of very cold air in valleys and hollows. Hoar frost may freeze in such low-lying cold air even when the air temperature a few feet above ground is well above freezing. The word "hoar" comes from an
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language English is a West Germanic language of the Indo-European language family The Indo-European languages are a language family A language ...
adjective that means "showing signs of old age". In this context, it refers to the frost that makes trees and bushes look like white hair. Hoar frost may have different names depending on where it forms: *Air hoar is a deposit of hoar frost on objects above the surface, such as tree branches, plant stems, and wires. *Surface hoar refers to fern-like ice crystals directly deposited on snow, ice, or already frozen surfaces. *Crevasse hoar consists of crystals that form in glacial crevasses where water vapour can accumulate under calm weather conditions. *
Depth hoar Depth hoar, also called sugar snow or temperature gradient snow (or TG snow), are large snow-crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly order ...
refers to faceted crystals that have slowly grown large within cavities beneath the surface of banks of dry snow. Depth hoar crystals grow continuously at the expense of neighbouring smaller crystals, so typically are visibly stepped and have faceted hollows. When surface hoar covers sloping snowbanks, the layer of frost crystals may create an
avalanche An avalanche (also called a snowslide) is a rapid flow of snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo fur ...

avalanche
risk; when heavy layers of new snow cover the frosty surface, furry crystals standing out from the old snow hold off the falling flakes, forming a layer of voids that prevents the new snow layers from bonding strongly to the old snow beneath. Ideal conditions for hoarfrost to form on snow are cold, clear nights, with very light, cold air currents conveying humidity at the right rate for growth of frost crystals. Wind that is too strong or warm destroys the furry crystals, and thereby may permit a stronger bond between the old and new snow layers. However, if the winds are strong enough and cold enough to lay the crystals flat and dry, carpeting the snow with cold, loose crystals without removing or destroying them or letting them warm up and become sticky, then the frost interface between the snow layers may still present an avalanche danger, because the texture of the frost crystals differs from the snow texture, and the dry crystals will not stick to fresh snow. Such conditions still prevent a strong bond between the snow layers. In very low temperatures where fluffy surface hoar crystals form without subsequently being covered with snow, strong winds may break them off, forming a dust of ice particles and blowing them over the surface. The ice dust then may form '' yukimarimo'', as has been observed in parts of Antarctica, in a process similar to the formation of dust bunnies and similar structures. Hoar frost and
white frost White is the lightness, lightest color and is achromatic (having no hue). It is the color of fresh snow, chalk and milk, and is the opposite of black. White objects fully diffuse reflection, reflect and scattering, scatter all the visible spec ...
also occur in man-made environments such as in freezers or industrial facilities. If such cold spaces or the pipes serving them are not well insulated and are exposed to ambient humidity, the moisture will freeze instantly depending on the freezer temperature. The frost may coat pipes thickly, partly insulating them, but such inefficient insulation still is a source of heat loss.


Advection frost

Advection frost (also called wind frost) refers to tiny ice spikes that form when very cold
wind Wind is the natural movement of air or other gases relative to a planet's surface. Wind occurs on a range of scales, from thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by th ...

wind
is blowing over tree branches, poles, and other surfaces. It looks like rimming on the edges of flowers and leaves, and usually forms against the direction of the wind. It can occur at any hour, day or night.


Window frost

Window frost (also called fern frost or ice flowers) forms when a glass pane is exposed to very cold air on the outside and warmer, moderately moist air on the inside. If the pane is a bad
insulator Insulator may refer to: * Insulator (electricity), a substance that resists electricity ** Pin insulator, a device that isolates a wire from a physical support such as a pin on a utility pole ** Strain insulator, a device that is designed to work i ...

insulator
(for example, if it is a single-pane window), water vapour condenses on the glass, forming frost patterns. With very low temperatures outside, frost can appear on the bottom of the window even with double-pane energy-efficient windows because the air convection between two panes of glass ensures that the bottom part of the glazing unit is colder than the top part. On unheated motor vehicles, the frost usually forms on the outside surface of the glass first. The glass surface influences the shape of crystals, so imperfections, scratches, or dust can modify the way ice . The patterns in window frost form a
fractal In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers (arithmetic and number theory), formulas and related structures (algebra), shapes and spaces in which they are contained (geometry), and quantities a ...

fractal
with a
fractal dimension In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...

fractal dimension
greater than one, but less than two. This is a consequence of the nucleation process being constrained to unfold in two dimensions, unlike a snowflake, which is shaped by a similar process, but forms in three dimensions and has a fractal dimension greater than two. If the indoor air is very humid, rather than moderately so, water first
condenses Condensation is the change of the physical state of matter from the gas phase In the physical sciences, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. E ...

condenses
in small droplets, and then freezes into
clear iceClear ice means a solid precipitation In meteorology Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates ...

clear ice
. Similar patterns of freezing may occur on other smooth vertical surfaces, but they seldom are as obvious or spectacular as on clear glass. File:Frost patterns 1.jpg File:Frost patterns 2.jpg File:Frost patterns 3.jpg File:Frost patterns 4.jpg File:Frost patterns 5.jpg File:Frost patterns 25.jpg File:WindowFrostNewmarketOntario1986.jpg File:Frost on a plastic container in a -30 C freezer.jpg


White frost

White frost is a solid
deposition Deposition may refer to: * Deposition (law), taking testimony outside of court * List of deposed politicians, Deposition (politics), the removal of a person of authority from political power * Deposition (university), a widespread initiation ritual ...
of ice that forms directly from water vapour contained in air. White frost forms when relative humidity is above 90% and the temperature below −8 °C (18 °F), and it grows against the wind direction, since air arriving from
windward 400px, Example image showing definitions of windward (upwind) and leeward (downwind) Windward () is the direction upwind from the point of reference, alternatively the direction from which the wind is coming. Leeward () is the direction downwin ...
has a higher humidity than leeward air, but the wind must not be strong, else it damages the delicate icy structures as they begin to form. White frost resembles a heavy coating of hoar frost with big, interlocking crystals, usually needle-shaped.


Rime

Rime is a type of ice
deposition Deposition may refer to: * Deposition (law), taking testimony outside of court * List of deposed politicians, Deposition (politics), the removal of a person of authority from political power * Deposition (university), a widespread initiation ritual ...
that occurs quickly, often under heavily humid and windy conditions. Technically speaking, it is not a type of frost, since usually
supercooled Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric process, isoc ...
water drops are involved, in contrast to the formation of hoar frost, in which water vapour desublimates slowly and directly. Ships travelling through Arctic seas may accumulate large quantities of rime on the rigging. Unlike hoar frost, which has a feathery appearance, rime generally has an icy, solid appearance.


Black frost

Black frost (or "killing frost") is not strictly speaking frost at all, because it is the condition seen in crops when the humidity is too low for frost to form, but the temperature falls so low that plant tissues freeze and die, becoming blackened, hence the term "black frost". Black frost often is called "killing frost" because white frost tends to be less cold, partly because the
latent heat Latent heat (also known as latent energy or heat of transformation) is energy released or absorbed, by a body or a thermodynamic system A thermodynamic system is a body of matter In classical physics and general chemistry, matter is any su ...
of freezing of the water reduces the temperature drop.


Effect on plants


Damage

Many plants can be damaged or killed by freezing temperatures or frost. This varies with the type of plant, the tissue exposed, and how low temperatures get; a "light frost" of damages fewer types of plants than a "hard frost" below . Plants likely to be damaged even by a light frost include vines—such as beans, grapes, squashes, melons—along with
nightshade The Solanaceae, or nightshades, are a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of familie ...
s such as tomatoes, eggplants, and peppers. Plants that may tolerate (or even benefit from) frosts include: *root vegetables (e.g. beets, carrots, parsnips, onions) *leafy greens (e.g. lettuces, spinach, chard, cucumber) *
cruciferous vegetables Cruciferous vegetables are vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, i ...

cruciferous vegetables
(e.g. cabbages, cauliflower, bok choy, broccoli, Brussels sprouts, radishes, kale, collard, mustard, turnips, rutabagas) Even those plants that tolerate frost may be damaged once temperatures drop even lower (below ). Hardy perennials, such as ''
Hosta ''Hosta'' (, syn. ''Funkia'') is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription ...

Hosta
'', become dormant after the first frosts and regrow when spring arrives. The entire visible plant may turn completely brown until the spring warmth, or may drop all of its leaves and flowers, leaving the stem and stalk only. Evergreen plants, such as pine trees, withstand frost although all or most growth stops.
Frost crack Frost crack or Southwest canker is a form of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree ...
is a bark defect caused by a combination of low temperatures and heat from the winter sun. Vegetation is not necessarily damaged when leaf temperatures drop below the freezing point of their cell contents. In the absence of a site the formation of ice crystals, the leaves remain in a
supercooled Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric process, isoc ...
liquid state, safely reaching temperatures of . However, once frost forms, the leaf
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison cell, a room used to hold peopl ...
may be damaged by sharp ice crystals. Hardening is the process by which a plant becomes tolerant to low temperatures. See also
CryobiologyCryobiology is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, ph ...
. Certain
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...
, notably ''
Pseudomonas syringae ''Pseudomonas syringae'' is a rod-shaped, Gram-negative Gram-negative bacteria are bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), ...
'', are particularly effective at triggering frost formation, raising the nucleation temperature to about . Bacteria lacking ice
nucleation Nucleation is the first step in the formation of either a new or a new structure via or . Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organized structure appear ...

nucleation
-active proteins ( ice-minus bacteria) result in greatly reduced frost damage.


Protection methods

Typical measures to prevent frost or reduce its severity include one or more of: *deploying powerful blowers to simulate wind, thereby preventing the formation of accumulations of cold air. There are variations on this theme. One variety is the wind machine, an engine-driven propeller mounted on a vertical pole that blows air almost horizontally. Wind machines were introduced as a method for frost protection in California during the 1920s, but they were not widely accepted until the 1940s and 1950s. Now, they are commonly used in many parts of the world. Another is the selective inverted sink, a device which prevents frost by drawing cold air from the ground and blowing it up through a chimney. It was originally developed to prevent frost damage to
citrus ''Citrus'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circums ...

citrus
fruits in
Uruguay Uruguay (; ; pt, Uruguai), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; whi ...

Uruguay
. In New Zealand,
helicopter A helicopter is a type of rotorcraft A rotorcraft or rotary-wing aircraft is a heavier-than-air aircraft An aircraft is a vehicle or machine that is able to fly Flies are insect Insects or Insecta (from Latin Latin (, ...

helicopter
s are used in similar fashion, especially in the
vineyard A vineyard ( , also ) is a plantation A plantation is a large-scale estate, generally centered on a plantation house, meant for farming that specializes in cash crops. The crops that are grown include cotton, coffee, tea, cocoa, sug ...

vineyard
regions such as
Marlborough Marlborough may refer to: Places United Kingdom * Marlborough, Wiltshire, England ** Marlborough College, public school * Malborough, village in Devon, England * Marlborough School, Woodstock in Oxfordshire, England * The Marlborough Science Acade ...
. By dragging down warmer air from the inversion layers, and preventing the ponding of colder air on the ground, the low-flying helicopters prevent damage to the fruit buds. As the operations are conducted at night, and have in the past involved up to 130 aircraft per night in one region, safety rules are strict.''Helicopters Fight Frost'' – ''Vector'',
Civil Aviation Authority of New Zealand The Civil Aviation Authority of New Zealand (CAA; Māori language, Māori: ''Te Mana Rererangi Tūmatanui o Aotearoa'') is the government agency tasked with establishing civil aviation safety and security standards in New Zealand. The CAA also mon ...
, September/ October 2008, Page 8-9
Although not a dedicated method,
wind turbine A wind turbine is a device that converts Religious conversion is the adoption of a set of beliefs identified with one particular religious denomination A religious denomination is a subgroup within a religion Religion is a social ...

wind turbine
s have similar (small) effect of vertically mixing air layers of different temperature.Turbines and turbulence
, ''
Nature (journal) ''Nature'' is a British weekly scientific journal In , a scientific journal is a intended to further the progress of , usually by reporting new . Content Articles in scientific journals are mostly written by active scientists such as st ...
'', 468, 1001, 23 December 2010, DOI:10.1038/4681001a, published online 22 December 2010.
Somnath Baidya Roy and Justin J. Traiteur
Impacts of wind farms on surface air temperatures
Proceedings of the National Academy of Sciences, Vol. 107, No. 42, October 19, 2010, p. 17,899.

, Science Daily.
*For high-value crops, farmers may wrap trees and cover crops. *Heating to slow the drop in temperature is not practical except for high-value crops grown over small areas. *Production of smoke to reduce cooling by radiation *Spraying crops with a layer of water releases latent heat, preventing harmful freezing of the tissues of the plants that it coats. Such measures need to be applied with discretion, because they may do more harm than good; for example, spraying crops with water can cause damage if the plants become overburdened with ice. An effective, low cost method for small crop farms and plant nurseries, exploits the latent heat of freezing. A pulsed irrigation timer delivers water through existing overhead sprinklers at a low volumes to combat frosts down to . If the water freezes, it gives off its latent heat, preventing the temperature of the foliage from falling much below zero.


Frost-free areas

Frost-free areas are found mainly in the lowland tropics, where they cover almost all land except at
altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum Data (; ) are individual facts A fact is something that is truth, true. The usual t ...

altitude
s above about near the equator and around in the semiarid areas in tropical regions. Some areas on the oceanic margins of the subtropics are also frost-free, as are highly oceanic areas near windward coasts. The most poleward frost-free areas are the lower altitudes of the
Azores The Azores ( , also ; pt, Açores ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal The two Autonomous Regions of Portugal ( pt, Regiões Autónomas de Portugal) are the Azores (''Região ...

Azores
,
Île Amsterdam Île Amsterdam (), also known as Amsterdam Island, New Amsterdam, or Nouvelle Amsterdam, is an island of the French Southern and Antarctic Lands in the southern Indian Ocean The Indian Ocean is the third-largest of the world's oceanic di ...
,
Île Saint-Paul Île Saint-Paul (Saint Paul Island) is an island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can ...

Île Saint-Paul
, and
Tristan da Cunha Tristan da Cunha (), colloquially Tristan, is a remote group of volcanic A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curv ...
. In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
, southern Florida around
Miami Beach Miami Beach is a coastal in , , . It was incorporated on March 26, 1915. The is located on natural and s between the and , the latter of which separates the Beach from the mainland city of . The of , comprising the southernmost of Miami ...

Miami Beach
and the
Florida Keys The Florida Keys are a coral island, coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of ...
are the only reliably frost-free areas, as well as the Channel Islands off the coast of
California California is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper i ...

California
. The
hardiness zone A hardiness zone is a geographic area defined as having a certain range of annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most w ...
s in these regions are 11a and 11b.


Personifications

Frost is personified in Russian culture as
Ded Moroz Ded Moroz (russian: Дед Мороз, , ; tt, / ; be, Дзед Мароз, ; uk, Дід Мороз, ; pl, Dziadek Mróz; Russian diminutive russian: Дедушка Мороз, ; sr, / ; bg, Дядо Мраз, ; sl, Dedek Mraz; sk, D ...

Ded Moroz
. Indigenous peoples of Russia such as the
Mordvins The Mordvins, also ''Mordva'', ''Mordvinians'', ''Mordovians'' ( myv, эрзят/''erzät'', mdf, мокшет/''mokšet'', russian: мордва/mordva), are a people A people is any plurality of person A person (plural people or pe ...
have their own traditions of frost deities. English folklore tradition holds that
Jack Frost Jack Frost is a personification of frost, ice, snow, Rain and snow mixed, sleet, winter, and freezing cold. He is a variant of Old Man Winter who is held responsible for frosty weather, nipping the fingers and toes in such weather, coloring the ...
, an elfish creature, is responsible for feathery patterns of frost found on windows on cold mornings.


Gallery

File:Frost on a nettle, Netherlands.jpg, Frost on a nettle File:Saskatoon-Frost.jpg, Large feathery crystals File:Fern Frost.JPG, Fern frost on a window File:Window-Frost.jpg, Window frost File:Frost on leaves.jpg, Frost on plant leaves in the
Himalayas The Himalayas, or Himalaya (; Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language of South Asia that belongs to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It ar ...

Himalayas
File:Hoar Frost.JPG, Surface hoar in
Alaska Alaska (; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Central Alaskan Yup'ik language, Yup'ik: ''Alaskaq''; tli, Anáaski) is a U.S. state in the Western United States, on the northwest extremity of the country's West Coast of the United State ...

Alaska
File:Hoar frost on a snow field.jpg, Hoar frost in
Julian Alps The Julian Alps ( sl, Julijske Alpe, it, Alpi Giulie, , ) are a mountain range of the Southern Limestone Alps that stretch from northeastern Italy to Slovenia, where they rise to 2,864 m at Mount Triglav, the highest peak in Slovenia and of the f ...
File:Frost on Birch Tree in Stockholm 20180110.jpg, Frost on birch tree in
Stockholm Stockholm (; ) is the capital Capital most commonly refers to: * Capital letter Letter case (or just case) is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smalle ...

Stockholm
File:Frost in Ranu Pani on 4 August 2018 by Susanto Tan 6.jpg, Frost on grass in Ranu Pani,
East Java East Java ( id, Jawa Timur) is a province A province is almost always an administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, administrative region, subnational entity, first-level su ...

East Java
,
Indonesia Indonesia ( ), officially the Republic of Indonesia ( id, Republik Indonesia, links=yes ), is a country in Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is t ...

Indonesia
File:Frost on birch tree.jpg, Frost on birch stem in
Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmål (, ; literally "book tongue") is an official written standard for the Norwegian language Norwegian (Norwegian: ''norsk'') is a Nort ...

Norway
File:Sydneyfrost.jpg, Frost on grass in
Sydney Sydney ( ; Dharug The Darug or Dharug people are an Aboriginal Australian people, who share strong ties of kinship and, in Colonial Australia, pre-colonial times, survived as skilled hunters in family groups or clans, scattered througho ...

Sydney
File:Leaf with frost.jpg, An oak leaf with frost in
Sweden Sweden ( sv, Sverige ), officially the Kingdom of Sweden ( sv, links=no, Konungariket Sverige ), is a Nordic country The Nordic countries, or the Nordics, are a geographical and cultural region In geography, regions are areas that ...

Sweden


See also

*
Black ice Black ice, sometimes called clear ice, is a thin coating of glaze ice Glaze or glaze ice, also called glazed frost, is a smooth, transparent and coating occurring when or hits a surface. It is similar in appearance to , which forms from ...

Black ice
*
Frost (temperature) Freezing, available onlinlibrary.wmo.int/ref> or frost occurs when the air temperature Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source ...

Frost (temperature)
*
Frost heaving Frost heaving (or a frost heave) is an upwards swelling of soil Soil (often stylized as SOiL) is an American rock band that was formed in Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interact ...

Frost heaving
*
Frost line The frost line—also known as frost depth or freezing depth—is most commonly the depth to which the groundwater Groundwater is the water Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly col ...
*
Frostbite Frostbite is a skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod ...

Frostbite
*
Ground frost Ground frost refers to the various coverings of ice Ice is water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it ...
*
Icing (nautical)Image:Iced ship1.jpg, 250px, Ice coating a United States Navy vessel Icing on ships is a serious hazard where cold temperatures (below about {{convert, -10, C, F, disp=or) combined with high wind speed (typically force 8 or above on the Beaufort scal ...
*
Needle ice Needle ice is a needle-shaped column of ice formed by groundwater. Needle ice forms when the temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in ...

Needle ice


References


External links


Guide to FrostHow much do you know about frost?
– ''BBC''
American Meteorological Society, ''Glossary of Meteorology'' – Hoarfrost
* {{Authority control Precipitation Psychrometrics Water ice