Picture posting is enabled for all :)
Air frostWhen the temperature in the Stephenson screen reaches zero, there is said to be an 'air frost'. Even with an air frost, the ground can sometimes stay above freezing. This often happens in early autumn, when the soil still retains some of its Summer heat. Normally though the temperature at ground level will be significantly colder!Ground frostSometimes the air temperature at night dips to 3 or 4 degrees, but the forecaster still warns of a 'ground frost' and the need to de-ice your car in the morning. This is because the ground can reach freezing while the air temperature remains above.Hoar frostThe white crystals seen on the grass on a cold morning are neither a ground nor an air frost. This is a 'hoar frost', which forms when the air cools and water condenses onto the grass.Hoar frost is very different from frozen dew, which is dew that has frozen after it has formed. They are very different to look at, frozen dew looks like frozen water droplets, and a hoar frost is a delicate icy structure.
Yesterday the bbc weather said there would be a night temp of 4 degrees on thursday but i have just logged on and it now says it will be 7 degrees