The best place I’ve ever been to watch the effects of a thunder storm was when I worked on the 13th floor of Charing Cross Hospital. I could look though the windows of my department and see lightening strikes all over west London. I seem to remember Fulham football club floodlights being hit.
I hadn’t realised until coming to write this article that those ferocious bolts and the deafening sounds started with the little fluffy clouds known as Cumulus. I found out about the process by finding the MetMatters website of The Royal Meteorological Society so over to them.
‘But how much do you really know about thunderstorms? It happens in three stages – the developing stage, the mature stage and the dissipating stage.
Cumulus clouds form when moist warm air rises, cools and condenses. If the updraught of warm air continues the cloud soon looks like a tower – hence the name towering cumulus. There is little to no rain at this developing stage but you can get occasional flashes of lightning.
The cloud will eventually grow upwards into areas where the temperature is below freezing, creating ice crystals that the upper level winds fan out to form the classic anvil shape at the top of a cumulonimbus cloud. Ice at the top of a tall cloud is an essential ingredient for the thunder and lightning associated with thunderstorms.
Thanks to the millions of collisions between the ice particles and water droplets bouncing around within the cloud, an electric charge builds up. When the electrical charge becomes sufficiently separated in a thundercloud, with some regions acquiring a negative charge and others a positive charge, a discharge of lightning becomes likely. In turn, a positive charge can build up on the ground beneath the cloud, on anything that sticks up such as mountains, people or trees.
When the charge coming up from the ground connects with the charge coming down from the clouds then – flash – we’ve got a lightning strike. The air surrounding the lightning channel briefly reaches temperatures of up to 30,000°C, causing the air to rapidly expand, which we hear as thunder. Thunder and lightning occur at roughly the same time, but you see the flash first as light travels much fast than sound.
We're now entering the mature stage of our storm when the updraught of rising air continues to feed the storm, but the water vapour in the cloud has formed heavy enough water droplets that precipitation begins to fall, and this creates a column of air pushing down. This downdraught and rain-cooled air spreads out along the ground to form a gust front. It's at this stage we're most likely to get hail, heavy rain, frequent lightning, strong gusty winds and even tornadoes.
Eventually, the rising updraught is overcome by the cool downdraught and the storm begins to dissipate. The gust front cuts off the warm moist air that was feeding the thunderstorm, rainfall decreases but lightning remains a danger until the storm is all rained out and often all that's left is a wispy anvil of cirrus cloud, high up in the sky.
The entire thunderstorm life cycle from growing cumulus cloud to dissipated storm takes an hour on average with less than 30 minutes of thunder and lightning. If it lasts longer then there is more than one storm cloud present.’
And it all started with a fluffy, white Cumulus. I think the RMetS have done a splendid job in explaining what can happen next.
I’d been looking for poems about Cumulus and clouds and there are some good ones but most of the time I was doing that I was humming along to Both Sides Now by Joni Mitchell from her Clouds album. It must be a sign.
https://www.youtube.com/watch?v=NfdOrNlrO-I
Rows and floes of angel hair
And ice cream castles in the air
And feather canyons everywhere
I've looked at clouds that way
But now they only block the sun
They rain and snow on everyone
So many things I would have done
But clouds got in my way
I've looked at clouds from both sides now
From up and down, and still somehow
It's cloud illusions I recall
I really don't know clouds at all
Moons and Junes and Ferris wheels
The dizzy dancing way you feel
As every fairy tale comes real
I've looked at love that way
But now it's just another show
You leave 'em laughing when you go
And if you care, don't let them know
Don't give yourself away
I've looked at love from both sides now
From give and take, and still somehow
It's love's illusions I recall
I really don't know love at all
Tears and fears and feeling proud
To say "I love you" right out loud
Dreams and schemes and circus crowds
I've looked at life that way
But now old friends are acting strange
They shake their heads, they say I've changed
Well something's lost, but something's gained
In living every day
I've looked at life from both sides now
From win and lose and still somehow
It's life's illusions I recall
I really don't know life at all
I've looked at life from both sides now
From up and down and still somehow
It's life's illusions I recall
I really don't know life at all
Rows and floes of angel hair
And ice cream castles in the air
And feather canyons everywhere
I've looked at clouds that way
But now they only block the sun
They rain and snow on everyone
So many things I would have done
But clouds got in my way
I've looked at clouds from both sides now
From up and down, and still somehow
It's cloud illusions I recall
I really don't know clouds at all
Moons and Junes and Ferris wheels
The dizzy dancing way you feel
As every fairy tale comes real
I've looked at love that way
But now it's just another show
You leave 'em laughing when you go
And if you care, don't let them know
Don't give yourself away
I've looked at love from both sides now
From give and take, and still somehow
It's love's illusions I recall
I really don't know love at all
Tears and fears and feeling proud
To say "I love you" right out loud
Dreams and schemes and circus crowds
I've looked at life that way
But now old friends are acting strange
They shake their heads, they say I've changed
Well something's lost, but something's gained
In living every day
I've looked at life from both sides now
From win and lose and still somehow
It's life's illusions I recall
I really don't know life at all
I've looked at life from both sides now
From up and down and still somehow
It's life's illusions I recall
I really don't know life at all
Thanks for reading, Terry Q.























