Frost & Fire (Adventure Time)
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Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above- freezing
atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) to ice (a solid) as the water vapor reaches the freezing point. 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 thermodynamics, nucleation is the first step in the formation of either a new thermodynamic phase or structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically defined to be the process that deter ...
. The ice crystals of frost form as the result of
fractal In mathematics, a fractal is a geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scales, as illu ...
process development. The depth of
frost crystals Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust. Formation The hugely symmetric shapes are due to depositional growth, na ...
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 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 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 Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its melting point without it becoming a solid. It achieves this in the absence of a seed crystal or nucleus around which a crystal ...
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: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
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.


Formation

If a solid surface is chilled below the dew point 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 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 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 The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will cond ...
of the air, meaning that it is sufficiently cold for ice to form without passing through 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 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 The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is n ...
, 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 into outer space faster than it can be replaced from nearby warm objects or brought in by the wind. Under suitable circumstances, objects cool to below the
frost point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will cond ...
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 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, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...
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-crystals occurring at the base of a snowpack that form when uprising water vapor deposits, or desublimates, onto existing snow crystals. Depth hoar cr ...
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 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 Dust bunnies (or dustbunnies) are small clumps of dust that form under furniture and in corners that are not cleaned regularly. They are made of hair, lint, flakes of dead skin, spider webs, dust, and sometimes light rubbish and debris and a ...
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 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 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 (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 nucleates. The patterns in window frost form a
fractal In mathematics, a fractal is a geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scales, as illu ...
with a 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 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. 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 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 a heavy coating of hoar frost with big, interlocking crystals, usually needle-shaped.


Rime

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 Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its melting point without it becoming a solid. It achieves this in the absence of a seed crystal or nucleus around which a crystal ...
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 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 of flowering plants that ranges from annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includes a number of agricultural crops, medicinal plants, spices, weeds, and orna ...
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 (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'', 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 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
nucleating In thermodynamics, nucleation is the first step in the formation of either a new thermodynamic phase or structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically defined to be the process that determ ...
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 or a gas below its melting point without it becoming a solid. It achieves this in the absence of a seed crystal or nucleus around which a crystal ...
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: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
may be damaged by sharp ice crystals. Hardening is the process by which 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 . Bacteria lacking ice nucleation-active proteins (
ice-minus bacteria Ice-minus bacteria is a common name given to a variant of the common bacterium ''Pseudomonas syringae'' (''P. syringae''). This strain of ''P. syringae'' lacks the ability to produce a certain surface protein, usually found on wild-type ''P. syrin ...
) 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 The selective inverted sink or SIS is a device used by farmers to protect plants from frost, developed by Uruguayan Rafael Guarga in the late 1990s. The sink is actually a large fan housed in a chimney-like structure, and works by defeating s ...
, 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 fruits in Uruguay. In New Zealand, helicopters are used in similar fashion, especially in the vineyard regions such as
Marlborough Marlborough may refer to: Places United Kingdom * Marlborough, Wiltshire, England ** Marlborough College, public school * Marlborough School, Woodstock in Oxfordshire, England * The Marlborough Science Academy in Hertfordshire, England Austral ...
. 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: ''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 monitors adherence ...
, September/ October 2008, Page 8-9
Although not a dedicated method, wind turbines have similar (small) effect of vertically mixing air layers of different temperature.Turbines and turbulence
, '' Nature (journal)'', 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 altitudes 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, Île Amsterdam, Île Saint-Paul, and Tristan da Cunha. In the
contiguous United States The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii ...
, southern Florida around
Miami Beach Miami Beach is a coastal resort city in Miami-Dade County, Florida. It was incorporated on March 26, 1915. The municipality is located on natural and man-made barrier islands between the Atlantic Ocean and Biscayne Bay, the latter of which sep ...
and the
Florida Keys The Florida Keys are a 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 Miami, and e ...
are the only reliably frost-free areas, as well as the Channel Islands off the coast of California. The
hardiness zone A hardiness zone is a geographic area defined as having a certain average 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 wide ...
s in these regions are 11a and 11b.


Personifications

Frost is personified in Russian culture as Ded Moroz.
Indigenous peoples of Russia Lists of indigenous peoples of Russia cover the indigenous ethnic groups in Russia other than Russians. As of 2010 these constituted about 20% of the population. The period lists are organized by the official classifications based on the number o ...
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.


Gallery

File:Frost on a nettle, Netherlands.jpg, Frost on a nettle File:Fern Frost.JPG, Fern frost on a window File:Dülmen, Hausdülmen, Distel -- 2021 -- 5079.jpg, Frost on a thistle in Hausdülmen, North Rhine-Westphalia, Germany File:Window-Frost.jpg, Window frost File:Frost on leaves.jpg, Frost on plant leaves in the Himalayas File:Hoar Frost.JPG, Surface hoar in Alaska File:Hoar frost on a snow field.jpg, Hoar frost in Julian Alps File:Frost on Birch Tree in Stockholm 20180110.jpg, Frost on birch tree in
Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...
File:Frost in Ranu Pani on 4 August 2018 by Susanto Tan 6.jpg, Frost on grass in Ranu Pani, East Java, Indonesia File:Frost on birch tree.jpg, Frost on birch stem in Norway File:Sydneyfrost.jpg, Frost on grass in
Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...
File:Leaf with frost.jpg, An oak leaf with frost in
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...


See also

* Black ice *
Frost (temperature) Freezing, available onlinlibrary.wmo.int/ref> or frost occurs when the air temperature falls below the freezing point of water (0  °C, 32  °F, 273 K). This is usually measured at the height of 1.2 metres above the ground surfac ...
* Frost heaving * Frost line * Frostbite * Ground frost *
Icing (nautical) 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 scale) result in spray blown off the sea freezing immediately on contac ...
*
Needle ice Needle ice is a needle-shaped column of ice formed by groundwater. Needle ice forms when the temperature of the soil is above and the surface temperature of the air is below . Liquid water underground rises to the surface by capillary action, a ...


References


External links


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