loading
City:

Jack Frost

Frost is a weather condition that occurs when the prevailing temperature falls below 0°C (32°F). It is recognized by the icy deposit that forms but if the air is very dry this will not occur.

A frost day is a period of 24 hours in which the minimum temperature in a thermometer screen is equal to or below 0°C (32°F). Occasionally the temperature can remain below freezing all day, known as an ice day.

Ice day is a period of 24 hours, beginning from 9:00 am, throughout which the maximum air temperature remains below 0°C. The average number of ice days per winter varies between 1 to 5 for much of England and Wales and 2 to 6 for Scotland. However, there are winters without a single ice day and winters, such as 1962-63, when Birmingham recorded 17 of them, for example.


In weather forecasting grades of severity of frost are distinguished as slight (-0.1 to -3.5°C), moderate (-3.6 to -6.4°C), severe (-6.5 to -11.5°C), and very severe or hard (below -11.5°C).


Air below 0°C is defined as air frost, measured at a height of 2m (6ft). Ground frost occurs when the air at ground level is chilled below freezing point. Ground frost is measured at 5cm (2in) above the ground. Hoar frost the fluffy deposit of minute ice crystals on grass and brickwork, occurs on calm, clear nights when condensation takes place after freezing. Black frost, as the name suggests, is a thin sheet of frost without the white colour usually associated with frost.


Frost hazard on roads is most common in maritime climates, such as in Scandinavia and the British Isles, where rainfall is regular and winter temperatures oscillate unpredictably around 0°C, and while salt is an effective de-icing agent it damages both road surfaces and vehicle bodies.


Frost is also an agricultural hazard; in 1971 the annual frost loss in the USA was estimated at USD 1.1 billion.



Add to social bookmarking:  | more |
A is for Air
Accessory clouds
Advection
Air masses and their sources
Air-mass Thunderstorm
Alpine Glow
Altocumulus
Anticyclone
Atmosphere - Diagram
Aurorae - Northern Lights
Average rainfall over England and Wales
Azores High
Banner Cloud - the peak's flag
Beaufort Scale
Blizzard
British Weather Terms
Brocken Spectre
Bubble High
Burning Time
CAPE - Convective Available Potential Energy
Cap cloud
Cc floccus
Cc lacunosus
Cc stratiformis
Cc undulatus
Central England Temperature
Centres of action
Ci fibratus
Ci radiatus
Ci spissatus
Ci uncinus
Ci vertebratus
Cirrocumulus
Cirrostratus
Cirrus
Clocks go Back from BST to GMT
Cloud classification
Cloud seeding
Cloud species
Cloud streets
Cloud types (genera)
Cloud variety
Clouds - sentry of the sky
Cold low
Comma Cloud
Comma Cloud
Convection
Coriolis effect
Corona
Crepuscular rays
Cut-off low
Dew Point
Dew
Discovery of the Jet Stream
Doppler radar
Drifting snow - blowing snow
Drought
Earth's Atmosphere
Easterly wave - the Hurricane's cradle
El Nino
Föhn (foehn) wind
Föhn wall
Flash Flood
Fog and Mist
Fogbow
Forecasting weather
Frost hollow
Fujita Scale Statistics
Fujita Tornado Scale
Funnel cloud
Genoa Low
Geostationary Satellites
Geostrophic Wind
Glaze and Black Ice
Glory
Grass Minimum Temperature
Gustnado
Hail
Hailstorms in Britain
Highs and Lows and Winds
History of Hurricane Names
Hoar Frost
Humidity
Inversions
Isobars on surface maps
Jack Frost
Jet stream cirrus from space
Katabatic winds
Key to our weather symbols
Lake-effect snow
Latent Heat
Levanter cloud
Millibar and hectopascal
Mirages
Mizzle
NOAA satellites
Nimbostratus
North Atlantic Drift (Gulf Stream)
Polar Orbiting Satellites
Polar low - the arctic hurricane
Precipitation Map
Radiosonde
Rain gauge
Rime
Roll cloud
Rotor cloud
Saffir-Simpson scales
Sc duplicatus
Sc perlucidus
Sc undulatus
Shelf Cloud
Sometimes a bit fishy
Sounding
Southern Oscillation
St. Swithun's Day
Standard Reference Period
Stevenson Screen
Stratocumulus
Stratosphere
Sun pillar
Supercooled clouds
Surface wind
Swell
TORRO
Thermocline
Thunderstorm Probability
Thunderstorms
Tornado Alley
Troposphere
Troposphere - Diagram
UV Index
Ultraviolet radiation
Virga or Fallstreak
What Makes Northern Lights Happen?
What does it mean?
Why Skies are Blue
Why Thunder Rumbles
World Meteorological Organisation (WMO)