Friday, 25 November 2011

A thought for the Faroes

It's just been on the weather that last night a gust of wind hit the Faroe Islands at over 120mph, 126mph I recall being mentioned. That is astonishing. Not unknown in the UK of course but astonishing, nonetheless.

This was all because of a deepening low pressure tracking across the North Atlantic, dropping 50 millibars in 36 hours. But it's better explained here.....

My maternal grandfather was a Master Ticket Sea Captain, which meant amongst other things he could go into any port without a pilot on board, which didn't make him the most popular man at times, as that's how pilots made their money. He plied the seas across the world in his ships, often away from home for up to two years at a time, and he was even seconded to the Royal Navy in the Second World War as an Atlantic Convoy leader (and harrowing that was apparently, as he watched "his" ships go down one by one while trying to maintain the formation and liaise with the Navy support). Bizarrely, when my parents met, Captain Johnson as my mother's father was always known, said to my father, "Dawes, are you related to "Daddy"Dawes..." my father said, "yes he's my grandfather". Captain Johnson then said, finest sea captain and ship owner I've ever served under, and with that nipped upstairs and got his first ever seaman's ticket, issued at the age of 14 when ships in sail were still being used. And there, on that ticket, which we still have, was my paternal great grandfathers signature, signing off the first rung of my maternal grandfather's shipping career. Being brought up in the North East, it was either shipping or mining that ruled the economy. Both sides of my family were shipping; all my paternal grandfathers brothers were sea captains, except him, he stayed on shore, at Readheads Dock in South Shields along with his sisters husband who was managing director at that time. It was my father who broke the mold and became an artist. But the sea is still in me, but from a safe distance of course....

I wish I had known my mothers father better. He was Norwegian and sadly died when I was 6 and although I can remember him, only vaguely. So my knowledge of him is from my mother. He always said respect the sea, the sea is in charge, you are not. And that has come down to me. I'm both fascinated and intimidated by the sea, especially when it is rough. I remember being in a force 10 coming back from the Isle of Arran and the ferry we were on was like matchsticks on a whirlpool. Seeing waves crash right over the ferry was absolutely fascinating, but then one remembers, we're in a fancy tin bath....... I hope the plug is in !

But I digress, this is about wind... I've paraphrased this from a weather facts website, as it is just so fascinating. Or at least I think so.

There is not a linear relationship between wind speed and the damage that is produced. For example, a 150 mph wind would not do twice as much damage as a 75 mph but rather it would produce many times over the damage of the 75 mph wind. When considering wind power alone there is a cubic relationship between wind speed and the power produced by the wind.

For example, suppose the wind speed is 15 mph and produces 3,375 units of power (15^3). If the wind speed is doubled to 30 mph then the power produced by the wind would be 27,000 units (30^3). As the wind speed increases the power produced increases at a rapid rate.

Assuming the cubic relationship mirrors reality which is does not for all wind speeds and situations, if the wind is 100 mph the damage produced will be 1,000,000 units of damage (100^3). If the units of damage are double to 2,000,000 then the wind speed that produced this damaged can be found by taking the cube root of 2,000,000 which has a value of 126 mph.

Thus, the damage produced increases significantly as the wind speed increases, especially as it increases above hurricane force. The 126 mph wind does twice the damage as the 100 mph although the increase in wind speed is about a fourth greater.

1 comment:

  1. My grandfather was also a sea captain. Actually, there's a bit about him in Farley Mowats book "The Serpents Coil". That's an awesome picture at the beginning of this post.