Originally Posted by Marksw76:
“A question for you weather experts...
Am I right in thinking HIGH pressure in the summer is hot and settled, and in the winter it's clear skies and cold/freezing nights?
If this is correct, then why do we always seem to have prolonged spells of cold freezing weather in January but very rarely do we get prolonged high pressure hanging around in the Summer bringing us weeks of hot sunshine?”
Short answer: Because we live in the UK and that's the way it is.
Long answer: Generally speaking that is correct. High Pressure and an easterly wind usually bring cold, dry and crisp weather in Winter and warm, dry and sunny weather in Summer.
With low pressure and a westerly wind the opposite scenario usually occurs - mild, wet and cloudy weather in Winter and cool, wet and cloudy weather in Summer.
The reason why we seem to get a lot more colder weather is probably down to our perception of the weather. In January and February in many places the average low temperature is around 1-4°C, so pretty cold, enough to give a light ground/car frost and of course as that's just the average there will be a lot of nights when it's colder than that. In Winter the average high temperatures range from about 6-9°C in most places which may seem mild to some but add in rain and wind etc and it will feel cold for many.
Also, there doesn't have to be high pressure in Winter for it to feel cold. Strong winds, rain, high humidity and an absense of sunshine will often make it feel colder. A strong northerly or north-westerly wind and polar maritime or arctic air, which typically brings cold weather with low pressure, rain and strong winds, can feel pretty chilly actually.
Speaking of which, Polar Maritime air is actually the most common air mass, which typically brings cold, rainy and showery weather in Winter and also (you guessed it) typically brings cold, rainy and showery weather in Summer, with the only difference being that temperatures will be higher in Summer.
Under this air mass, temperatures will typically be around 4-8°C during the Winter and around 13-19°C during the day in Summer.
We also get a lot of Tropical Maritime air which typically brings mild, wet and cloudy weather in Winter and warm, wet, humid, muggy and cloudy weather in Summer. Under this air mass, temperatures will typically be around 8-13°C during Winter and about 15-24°C during the day in Summer.
The air mass which typically gives us very hot dry weather in Summer is called the Tropical Continental Air Mass and gives us that hot, dry, sticky and sunny weather many of us love (and hate!) in Summer. It originates from North Africa but it doesn't call very often and when it does it doesn't usually last long. Our highest temperatures usually occur under the influence of this air mass (over 30 °C by day and around 15 to 20 °C at night).
The Polar Continental air mass (which originates from Central Europe) typically gives us cold (but not necessary dry!) weather in Winter, as usually it gives us that cold, crisp and frosty weather I talked about earlier but occasionally it can give snow as well! Especially if the air is coming from a very cold place such as Siberia... It typically gives pleasant warm sunny weather in Summer but usually nothing extremely hot unlike the Tropical Continental air.
You can read more about air masses here:
http://www.metoffice.gov.uk/learning...r-masses/types
In the Summer average high temperatures generally range from about 18-22°C in most places in the UK (excluding Northern Scotland) which isn't particularly hot, just average room temperature really (though it can feel very warm if there is unbroken sunshine or high humidity or you are wearing thick clothing etc).
Also, a hot, dry spell in Summer in the UK is often soon interrupted by thunderstorms as the higher temperatures cause friction and unsettled weather in the atmosphere lowering the pressure, typically giving short, sharp showers and heavy rain.
Whereas there is nothing really to interrupt a cold spell in Winter except perhaps a mild south westerly blast from the Atlantic.
Hope I answered your question.