Hoar Frost - You Ask We Answer
Is this the famous English hoarfrost we have all read about! PS Our high school song spoke of the hoary walls and we all laughed in teenage ignorance!
I was just going to give a quick answer in my comments, but what better topic is there for You Ask We Answer than the great British weather? So the YAWA staff here sprang into action immediately to find out.
The word hoar comes from the Middle English hor, which in turn comes from the Old English har. It's related to Old High German, which makes me wonder if there's a connection to the German word haar (hair), which we're singing about in Silent Night at choir at the moment. Hoar itself has two meanings: the first is ancient, such as a hoary beard, which means one whitened with age, just like NAH's! The second is white, thus giving us the descriptive white frost, sometimes used instead of hoar.
The BBC Weather Pages says hoar frost forms when the air cools so that water condenses out of the air onto garden surfaces such as grass, plants, or as my photos showed on Monday, sheds and fences. This is quite different to frozen dew which looks like frozen water droplets, whereas hoar frost has a delicate, ice crystal structure. According to WeatherOnline, the objects the water condenses onto must also be below freezing and the resultant hoar frost looks like needles, feathers and spines. It also suggests that the air must be supersaturated with water i.e. above 100% humidity for this effect to take place. Hoar frost shouldn't be confused with rime, which forms from freezing fog, or glaze which forms as a continuous sheet of ice. Unlike hoar frost, both aren't formed from individual frozen droplets.
The BBC website gives two further definitions: Air frost is when the air temperature reaches zero degrees centigrade (32 degrees Fahrenheit), though the ground can sometimes stay above freezing. This often happens in early autumn, as the soil still retains some of its summer heat. Ground frost is when the ground's surface temperature reaches zero. This can happen even though the air temperature may remain above, at say 3 or 4 degrees centigrade.
On very special days hoar frost gives us that 'winter wonderland' effect, which when combined with sunshine can be magical - as shown in this magnificent photograph. There's also an apple called Hoary Morning, originating from Somerset in 1819. Its skin has a deep bloom like hoar frost, hence the name.
So Gail, I suppose the short answer to your question is yes, my photos did show hoar frost, but I hope you've enjoyed my longer explanation and a further picture from Sunday. Now, how did your hoary high school song go? ;)