Weather watch
It’s the nation’s classic go-to conversation, so check out our need-to-know nuggets, then look to the skies
Be it snow in April, balmy barbecue conditions in October or torrential rain on a sweaty summer’s evening, the UK climate can be pretty bonkers. But Tristan Gooley makes it his mission to understand the mysteries of meteorology.
Here are his findings…
RAIN GHOSTS IN THE SKY
TOTALLY UNIQUE
No two clouds are exactly
the same. Even if they were, they wouldn’t look identical. The atmosphere alters the colours that we
see with the naked eye as the sun casts shadows within and on the clouds. And those very clouds change by the second,
too. Crafty!
You know the rain we can sometimes see, but never feel? It’s called virga and consists of droplets or ice crystals that are just large enough to fall, but not substantial enough to make it through the drier air all the way to the ground. If there’s a strong wind at cloud level, the streaks can be seen falling away behind the cloud, dropping into the slower wind below. Tristan says they remind him of cartoon ghosts floating, the “bodies” fading into trailing wisps behind them. Hence the name he’s given them: rain ghosts.
SIZE MATTERS
The size of a snowflake can give us a clue about the temperature of the air. Tristan explains that if the snowflakes are large, this indicates the air is actually warm. If they’re getting bigger, it tells us that it could soon stop snowing. If the flakes shrink, it’s a sign of falling temperatures. Brrr!
BEWARE RAGGED BOTTOMS
Rain rarely falls from small, cute cumulus clouds, and if they’re wider than they are tall, it’s very unlikely. As a general rule, smooth-based cumulus clouds mean put your umbrella away, but ragged bottoms indicate rain. These uneven fragments of cloud are called “pannus”. Tristan thinks of them as rain’s footprints.
A STORMY WARNING
The dramatic sight of “castles in the sky” – dozens or even hundreds of cumulus clouds in the shape of towers or turrets – is an early warning sign of thunderstorms. To get technical, they’re called altocumulus castellanus and are a strong sign of a wide blanket of moist unstable air bringing storms within hours. Take cover!
IT’S ELECTRIC!
The idea that lightning never strikes twice is wishful thinking – the Empire State Building in New York was once struck 15 times in 15 minutes! But this little nugget is true: the colour of lightning can give us a clue about the air it’s passed through. If the lightning is white, the air is dry; if it’s red, the air is dusty; if it’s blue, it has just passed through hail.
JOURNEY’S END
The raindrops that fall on us are at the end of a very long journey, having started life high above us as snow or ice. When they hit the ground, the earthy scent you can smell in the air is called “petrichor”, and occurs when the rain mixes with the oils and bacteria in the soil.