It’s two and a half months since the Winter Equinox or ‘shortest day of the year’ – December 21, and we’re finally starting to notice the lighter mornings and evenings.
Here in Bucks, the sun is now at the same strength as in the first week of October.
How come then, it still feels like winter – albeit a wet and windy rather than snowy one – with temperatures struggling and certainly not comparable to those in early October?
Indeed, on average in early March, Bucks can still expect an air frost on around one in every three nights, compared to just two in the whole of a typical October.
Well, the culprit for this delayed end to the winter cold is the same one that has been causing many of our other recent weather-woes – water. Seventy per cent of the earth’s surface is covered by seas and oceans, and here in the UK we are, of course, surrounded by them!
Water has a large heat capacity and thus requires lots of heat to warm up.
So although the sun is now significantly stronger than 11 weeks ago, sea temperatures are still only around their annual minimum.
Whilst the sun increases in strength markedly over the coming months, sea temperatures lag well behind, as anybody who has ever dipped their toes into the water along our coastline will testify to!
The sun is ‘strongest’ on June 21, but sea temperatures don’t reach their maximum until late August or early September – the main reason why our warmest period climatologically is several weeks after the Summer Equinox.
Whilst we may not yet be benefitting personally from the strengthening sun, the environment around us certainly is.
Flowers are starting to bloom, the grass is beginning to grow, birds are singing earlier and louder each day, whilst the stronger solar radiation allows road surface temperatures to climb 10-15C higher than on a sunny day with a similar air temperature in mid-December.
This extra heat gained during the daytime reduces the chance of road frosts overnight.
And the forecast?
Well, milder than the past few days and mostly dry too. Bright today, more cloud tomorrow and Friday, but then perhaps some sunshine over the weekend!