© Lorem ipsum dolor sit Nulla in mollit pariatur in, est ut dolor eu eiusmod lorem 2014
Weather Glossary
Frost and Ice
They are several types of weather common to the UK below is a quick description
Ground Frost
Ground frost occurs where ice forms on the ground where the temperatures has fallen below the
freezing point of water. Ground frost occurs more frequently than Air frost due to the fact that the
ground can lose heat much quicker than the surrounding air. In recent times lazy presentations on the
TV have allowed the term grass frost to be used. This is unofficial and inaccurate and the term
shouldn’t be used. I can’t see the term Windscreen frost be used when Ice only forms on Car
Windscreens. The only reason why frost is more prevalent on Grass at times is because concrete can
hold onto the heat better. However the correct terms are Ground Frost and not Grass Frost.
Air Frost
An Air Frost occurs when the temperature falls below the freezing point of water at a height of at least
One Meter above ground.
Image by http://www.hd2wallpapers.com
Hoar Frost may also form from dew as temperatures drop to around -3C to -5C. This also know as
Silver Frost or White frost. Hoar frost can also be derived from sublimation. It’s also easy to confuse
Hoar frost with Rime or Glaze.
Rime
Rime is a granular deposit of ice which maybe white or Milky in appearance. This is formed by rapid
freezing of super cooled water on cold exposed objects. Rime may also form feathers which point
into the wind. Under calm conditions they may form in any direction. This why it’s confused with
Hoar Frost. Rime is created via foggy conditions or by cloud droplets. These droplets which are
supercooled freeze as soon as they make contact with any object. If the fog persists large amounts of
ice can be formed. This may cause structural damage.
Glaze or Black Ice
Glaze forms when supercooled liquid precipitation falls in the form of freezing rain or drizzle onto
exposed objects at or just above zero. The liquid doesn’t freeze instantly allowing the liquid to spread
out forming a thin layer of smooth ice.
Unlike Hoar Frost or Rime the glaze is transparent. Glaze or Black ice tend to occur when a warm air
mass displaces a cold air mass.