Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is similar to the formation of dew , except it occurs below the freezing point of water typically without crossing through a liquid state.
56-515: Tyntynder is a locality in the south-east of the Mallee region of Victoria , Australia . Tyntynder Football Club is an Australian rules football team in the Central Murray Football League . Tyntynder post office opened on 4 May 1894, then it was renamed Nyah Post Office 1 November 1894, but closed on 8 August 1944. At the 2016 census , Tyntynder and the surrounding area had
112-467: A "hard frost" below −2 °C (28 °F). Plants likely to be damaged even by a light frost include vines—such as beans, grapes, squashes, melons—along with nightshades such as tomatoes, eggplants, and peppers. Plants that may tolerate (or even benefit from) frosts include: Even those plants that tolerate frost may be damaged once temperatures drop even lower (below −4 °C or 25 °F). Hardy perennials, such as Hosta , become dormant after
168-438: 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 (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
224-475: A heavy coating of hoar frost with big, interlocking crystals, usually needle-shaped. Rime is a type of ice deposition that occurs quickly, often under heavily humid and windy conditions. Technically speaking, it is not a type of frost, since usually supercooled 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
280-600: A plant becomes tolerant to low temperatures. See also Cryobiology . Certain bacteria , notably Pseudomonas syringae , are particularly effective at triggering frost formation, raising the nucleation temperature to about −2 °C (28 °F). Bacteria lacking ice nucleation-active proteins ( ice-minus bacteria ) result in greatly reduced frost damage. Typical measures to prevent frost or reduce its severity include one or more of: 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
336-512: A population of 151. This article about a location in the Mallee is a stub . You can help Misplaced Pages by expanding it . The Mallee The Mallee is a sub-region of Loddon Mallee covering the most north-westerly part of Victoria , Australia and is bounded by the South Australian and New South Wales borders. Definitions of the south-eastern boundary vary, however, all are based on
392-479: A process similar to the formation of dust bunnies and similar structures. Hoar frost and white frost also occur in man-made environments such as in freezers or industrial cold-storage 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
448-473: Is 40,183 square kilometres (15,515 sq mi). An area of South Australia immediately to the west of the Victorian Mallee region, also once covered with mallee scrub, is commonly referred to as the " Murray Mallee " or "the Mallee". The Mallee is, for all practical purposes, completely flat and very low-lying: in fact, for long geological periods the whole region was inundated by the ocean . Most of
504-520: 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 in small droplets, and then freezes into 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. White frost
560-431: Is a solid deposition 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 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
616-413: Is a source of heat loss. Advection frost (also called wind frost ) refers to tiny ice spikes that form when very cold 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 (also called fern frost or ice flowers ) forms when
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#1733106665852672-441: Is also significant industry. Mildura and Swan Hill contain a number of tourism focused businesses, including a number of specially built attractions and festivals. The Murray itself is also a major attraction, many people coming to the district for fishing and to stay on houseboats . The many Mallee national parks - Wyperfeld , Hattah-Kulkyne and Murray Sunset National Parks, wilderness parks, state forests, and other parks over
728-406: Is called "killing frost" because white frost tends to be less cold, partly because the latent heat of freezing of the water reduces the temperature drop. 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 −2 to 0 °C (28 to 32 °F) damages fewer types of plants than
784-633: 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. 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 into outer space faster than it can be replaced from nearby warm objects or brought in by
840-460: Is forced out of solution, resulting in a phase change directly from water vapor (a gas ) to ice (a solid). As more water molecules are added to the seeds, crystal growth occurs, forming ice crystals . Crystals may vary in size and shape, from an even layer of numerous microscopic-seeds to fewer but much larger crystals, ranging from long dendritic crystals (tree-like) growing across a surface, acicular crystals (needle-like) growing outward from
896-418: Is generally on a small scale and confined to food processing. Wheat and barley are widely grown on the less infertile soils in the southeast of the region, but fertilizers , especially superphosphate are essential for success and yields only a quarter of those in most of Europe or North America - in drought years, they can be as little as one twentieth of European wheat yields. Fruit growing along
952-411: Is not necessarily damaged when leaf temperatures drop below the freezing point of their cell contents. In the absence of a site nucleating the formation of ice crystals, the leaves remain in a supercooled liquid state, safely reaching temperatures of −4 to −12 °C (25 to 10 °F). However, once frost forms, the leaf cells may be damaged by sharp ice crystals. Hardening is the process by which
1008-543: Is personified in Russian culture as Ded Moroz . Indigenous peoples of Russia such as the Mordvins have their own traditions of frost deities. English folklore tradition holds that Jack Frost , an elfish creature, is responsible for feathery patterns of frost found on windows on cold mornings. In 2024, two European Space Agency spacecraft, Exomars TGO and Mars Express , discovered a thin but very wide layer of water frost on
1064-558: Is sometimes referred to as an economic region , of the Australian state of Victoria . The district is located entirely within the Victorian government's "Loddon Mallee region". People in the central Mallee sometimes believe that "the Mallee" only includes the dryland farming portion of the region. Frost Air always contains a certain amount of water vapor, depending on temperature. Warmer air can hold more than colder air. When
1120-458: Is used to describe the Wimmera district and a small part of the Mallee that is relatively close to Horsham. A separate tourism district known as Mildura Swan Hill covers the rural cities of Mildura and Swan Hill. The term Wimmera Mallee has also been used by the federal member for Mallee to describe their electorate, as the electorate covers both regions more-or-less in their entirety. The Mallee
1176-526: Is usually only produced by the most vigorous frontal systems or by occasional penetration of tropical air in the summer. Average annual rainfall shows a well-defined north–south gradient: Mildura averages only 267.9 millimetres (10.55 in) per year but Hopetoun in the south receives around 370 mm (15 in). Variability, however, is quite high : in 1973 the Mallee averaged as much as 650 mm (26 in) but in 1982 only 115 mm (4.5 in). Temperatures in summer are generally very hot: during
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#17331066658521232-461: The Buloke , Gannawarra , Mildura City and Swan Hill City local government areas . Another common definition is that the Mallee is the part of Victoria dependent on Mildura and Swan Hill . The Victoria State Government has historically had many departmental regions combining the Mallee with the greater Bendigo area, the current one being named the "Loddon Mallee" region. This region includes
1288-539: The Early 2009 southeastern Australia heat wave , Hopetoun reached 48.8 °C (119.8 °F) and the average maxima in January and February are 32.7 °C (90.9 °F). In July, maximum temperatures average 15.4 °C (59.7 °F), but minima average 4.4 °C (39.9 °F) and frosts are very common. In his 1939 paper on the physiography of North-Western Victoria, E.S. Hills stated that: "the chief factors involved in
1344-504: The Loddon River catchment and adjacent areas as well as the Mallee. This region is used by all state government departments, and often there is a central body for the region located in Bendigo. In 2005, there were attempts to push for a separate region in north-west Victoria in the belief that this would deliver more services to the district. For tourism purposes, the term Wimmera Mallee
1400-536: The Wimmera River to the south supplies Lake Hindmarsh and, very occasionally (in 1918, 1956 and 1975), overflows to the north. The Murray River is, thus, the only source of fresh water for the region and is consequently overburdened by intensive irrigation . As of 2019, 61% of the area utilizes drip irrigation . The climate of the Mallee is the hottest and driest in Victoria owing to its inland location. Rainfall
1456-433: The atmosphere contains more water than it can hold at a specific temperature, its relative humidity rises above 100% becoming supersaturated , and the excess water vapor is forced to deposit onto any nearby surface, forming seed crystals . The temperature at which frost will form is called the dew point , and depends on the humidity of the air. When the temperature of the air drops below its dew point, excess water vapor
1512-527: The contiguous United States , southern Florida around Miami Beach and the Florida Keys are the only reliably frost-free areas, as well as the Channel Islands off the coast of California . The hardiness zones in these regions are 11a and 11b. Permafrost is a layer of frozen earth underground which never heats above freezing even during summer months, remaining frozen year round. Although not frost in
1568-418: The 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 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
1624-533: The Earth to reach deep enough to thaw the permafrost layer. The permafrost may begin from the surface of the ground or many meters beneath it, and may extend from just a meter to over a thousand meters in thickness. Permafrost contains a significant portion of the Earth's water and carbon, and prevents surface water from penetrating very deep into the ground, making it responsible in part for the typical taiga and spruce bog environments common in northern latitudes. Frost
1680-513: The Mallee consists of sand dunes that have been deposited as a result of movement of sand from the interior of Australia during arid glacial periods of the Quaternary . The soils are generally very infertile and sandy: the better ones on more stabilised sand dunes in the east are slightly loamy and pink to light brown and have been able to support wheat and barley growing as a result of the development of superphosphate and other fertilisers . In
1736-555: The Mallee is spread over parts of both the Murray Darling Depression and Riverina bioregions . The Mallee is one of the nine districts in Victoria used for weather forecasting by the Australian Bureau of Meteorology . The Victorian Department of Environment and Primary Industries defines the district as a 39,300-square-kilometre (15,200 sq mi) region for agricultural production purposes encompassing
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1792-536: The Murray River exceeds grain crops as the Mallee's major source of revenue. Oranges and grapes are particularly important and the region produces a large part of Victoria's wine though most of it is inexpensive cask wines. Dairying on irrigated pastures is important in the south of the region, but is threatened by its high water demand and the extreme scarcity of water in the Murray-Darling Basin. Tourism
1848-424: The air is very cold, calm, and heavily saturated, such as during an ice fog . Frost may occur when warm, moist air comes into contact with a cold surface, cooling it below its dew point, such as warm breath on a freezing window. In the atmosphere, it more often occurs when both the air and the surface are below freezing, when the air experiences a drop in temperature bringing it below its dew point, for example, when
1904-462: The air temperature a few feet above ground is well above freezing. The word "hoar" comes from an Old English 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: When surface hoar covers sloping snowbanks, the layer of frost crystals may create an avalanche risk; when heavy layers of new snow cover
1960-461: The atmospheric sense, it consists of dirt, soil, sand, rocks, clay, or organic matter (peat) bound firmly together by ice crystals, making the material very hard and difficult to penetrate. Permafrost exists in the colder climates of the Arctic and Antarctic, such as Russia, Canada, Alaska, Norway, Greenland, or Antarctica, where the warmer conditions of summer are insufficient to penetrate the insulation of
2016-399: 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 nucleates . The patterns in window frost form a fractal with a fractal dimension greater than one, but less than two. This
2072-452: 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 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
2128-452: The distinction between the Mallee and the country south and east of it are precipitation, evaporation, rock type, porosity of the superficial deposits, drainage away from high areas and supply of water from streams that rise in regions of higher rainfall." At the 2011 census, the Mallee had a population of 81,544, most of which live close to the Murray River in the district's two cities, Mildura and Swan Hill. These and other settlements within
2184-407: 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 is a bark defect caused by a combination of low temperatures and heat from the winter sun. Vegetation
2240-414: 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
2296-405: 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
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2352-420: The historic Victorian distribution of mallee eucalypts. These trees dominate the surviving native vegetation through most of Mallee, (except for swamps and areas along waterways). Its biggest settlements are Mildura and Swan Hill . At the 2011 census , the four local government areas (LGAs) that are usually thought to define the district had a combined population of 88,178. The area of these same four LGAs
2408-523: The lowland tropics, where they cover almost all land except at altitudes above about 3,000 metres or 9,800 feet near the equator and around 2,000 metres or 6,600 feet 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 , Île Amsterdam , Île Saint-Paul , and Tristan da Cunha . In
2464-439: The municipalities based on these centres contain over two-thirds of the region's population. Ouyen and Murrayville are the main settlements of the central Mallee, while Kerang , Cohuna , Hopetoun and Birchip are the major towns in the south. The Mallee is a primarily agricultural region: apart from possible mineral sands in the west and salt from certain ephemeral lakes there are no mineral deposits of value and industry
2520-466: 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 −5 °C (23 °F). If the water freezes, it gives off its latent heat, preventing the temperature of the foliage from falling much below zero. Frost-free areas are found mainly in
2576-811: The result of 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 ). Frost crystals may be invisible (black), clear ( translucent ), or, 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 or radiation frost) from deposition of water vapor from air of low humidity, white frost in humid conditions, window frost on glass surfaces, advection frost from cold wind over cold surfaces, black frost without visible ice at low temperatures and very low humidity, and rime under supercooled wet conditions. Plants that have evolved in warmer climates suffer damage when
2632-411: The rigging. Unlike hoar frost, which has a feathery appearance, rime generally has an icy, solid appearance. 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
2688-682: The river are also major drawcards. The Wergaia people are an Aboriginal Australian group in the Wimmera and Mallee regions. The people were also known as the Maligundidj (in the Wotjobaluk language ) which means the people belonging to the Mali (mallee) bushland, which covers part of their territory. This name has also been recorded as Malleegunditch . In the context of the Interim Biogeographic Regionalisation for Australia ,
2744-432: 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
2800-407: 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 may also be called atmospheric icing . The ice it produces differs in some ways from crystalline frost, which consists of spicules of ice that typically project from
2856-432: The surface, snowflake-shaped crystals, or even large, knifelike blades of ice covering an object, which depends on many factors such as temperature, air pressure, air motion and turbulence, surface roughness and wettability , and the level of supersaturation. For example, water vapor adsorbs to glass very well, so automobile windows will often frost before the paint, and large hoar-frost crystals can grow very rapidly when
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#17331066658522912-523: The temperature falls after the Sun sets. In temperate climates , it most commonly appears on surfaces near the ground as fragile white crystals ; in cold climates, it occurs in a greater variety of forms. The propagation of crystal formation occurs by the process of nucleation , in specific, water nucleation , which is the same phenomenon responsible for the formation of clouds, fog, snow, rain and other meteorological phenomena. The ice crystals of frost form as
2968-421: The temperature falls low enough to freeze the water in the cells that make up the plant tissue . The tissue damage resulting from this process is known as "frost damage". Farmers in those regions where frost damage has been known to affect their crops often invest in substantial means to protect their crops from such damage. If a solid surface is chilled below the dew point of the surrounding humid air, and
3024-489: 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
3080-433: The west, the soils are unconsolidated sands, much less alkaline than in the east, and not generally able to support any grain cropping. The Mallee has no surface drainage: the native vegetation has so high a rooting density that the rainfall of most years is easily absorbed and the porous sandy soils mean that any excess in an exceptionally wet year will recharge groundwater supplies which tend to be highly saline. Flow from
3136-428: The wind. 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 cools 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
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