- The UK has variable weather, so the sun may come out one minute and it may rain the next
- MailOnline talks to meteorologists why Britain’s weather is so ‘unique’
- This is partly due to the five main air masses battling for supremacy over Britain.
- But where Britain is in the world, a large land mass to the east and the ocean to the west, as well as the jet stream, also has a major impact at altitudes of 30,000 feet.
Hot and sunny one minute, rainy the next, sometimes British weather can be so wildly variable it’s hard to keep up.
Last month too, after a largely benign summer, it offered another surprise by bringing on September’s heatwave, which was suddenly halted by a thunderstorm and more heavy rain.
But why is it so variable and likely to change from day to day? Or even to the desperation of those who have forgotten a coat hour after hour?
And has climate change affected it?
MailOnline spoke to several meteorologists about what makes Britain’s weather so ‘unique’, as one put it, and whether any other country in the world compares to it.
What season will we get? There are five main air masses that fight it over Britain. These include polar oceanic, arctic marine, polar continental, tropical continental and tropical marine. A sixth air mass, known as the Returning Polar Maritime, also affects the UK.
Hot and sunny one minute, rainy the next, sometimes British weather can be so wildly variable it’s hard to keep up. But why is it so variable and likely to change from day to day? MailOnline spoke to several meteorologists to find out (stock image)
At its center are five main air masses. These battles for supremacy over Britain and when they collide can create an extraordinary mix of atmospheric conditions. Each brings different weather but it’s the one who wins that decides whether we get the hot sun or not (stock image)
What are the main air masses moving over Britain?
There are five main air masses over Britain, as well as a sixth one which is a variation of one of them.
The UK is more likely to receive sea air masses because our weather comes mainly from the west. This is because the direction in which the Earth rotates gives us the experience of prevailing westerly winds.
Although Britain receives Hawaiians from the east, they are not as common as forecasters say.
Coming from Greenland and the Arctic Sea, it brings wet and cold air that causes cold and rainy weather.
As its name suggests, this air mass comes from the Arctic. It brings with it wet and cold air which causes snowfall in winters.
When East from the Beast invaded Britain in 2018, the bone-cooling air was polar continental and came from Siberia. It brings warm air in summer and cold in winter, leading to dry summers and snowy winters.
Everyone’s favorite summer air mass is the tropical continental one that gives us heat waves and bags of sunshine. The air is hot and dry and comes from North Africa.
This warm and moist air coming from the Atlantic Ocean brings clouds, rain and mild temperatures to the UK.
polar sea is returning
The returning polar sea is a variation of the polar sea.
However, it moves the wind first south over the North Atlantic, then north-east across the UK.
While moving south, the air becomes unstable and moist, but as it moves northeast, it passes over cold water, making it more stable.
This brings largely dry weather and clouds.
At its center are five main air masses that each have similar temperature and moisture properties. They battle for supremacy over Britain and when they collide can create an extraordinary mix of atmospheric conditions.
‘The UK doesn’t have its own weather,’ said Met Office forecaster Aidan McGivern, ‘it borrows it from elsewhere.
‘This is what air masses are – large bodies of air that come from other places.’
Professor Liz Bentley, CEO of the Royal Meteorological Society, said: ‘When two air masses are next to each other, we get dramatic weather conditions.
‘Air masses are dependent on wind direction; If they come from the continent they are continental, from the north they are polar, from the ocean they are oceanic and from the south they are tropical.’
These include polar oceanic, arctic marine, polar continental, tropical continental and tropical marine. A sixth air mass, known as the returning polar ocean, is also observed over Britain and is a variation of the polar ocean.
Each air mass brings a different type of weather, but as they meet and fight it, it is the one who wins that decides whether we get hot sun, cold rain or a spectacular thunderstorm.
“The predominant air mass over the past weekend was tropical oceanic, where moisture-laden warm air is drawn in from tropical and subtropical regions, leading to mild, cloudy and humid weather,” McGivern said.
‘Now we’ve changed it to the polar oceanic air mass which still brings clouds but is very cold.
‘We get a predominantly sea breeze, either the Tropical Maritime, the Polar Maritime or the Returning Polar Maritime, because of how the Earth rotates, causing the prevailing westerly winds to the UK.’
Professor Bentley said: ‘Although all air masses play a role, the prevailing wind direction for us is westerly so we see more coming from the Atlantic.
‘The time of year doesn’t affect which air mass wins, but when one does, depending on what season we are in, which season we get.
‘In winter, the air from the continent is very cold. That’s why in 2018 we had the beast from the east – because of the cold air coming in from Siberia.
‘However, in the summer, when tropical continental air masses are more common, the air is warmer because it is coming from a very hot continent, so you are likely to get a heatwave.’