Tag Archives: weather

A weather-related ‘Did you know?’ post

Did you know that wintry weather is more likely in March than December in the UK? On average, snow falls on five days in December. In March, it falls on six days.

That makes no difference to my wish for this seemingly endless winter to begone, though. Honestly, it seems to have been going on forever. And I’m not being fooled: look at this picture. This is my back garden.

Don't be fooled. It may look lovely and sunny and warm in my back garden, but it's brass monkeys out there.

Doesn’t it look lovely and Spring-like?

I just went outside to put the washing out, and my fingers froze solid. I’m typing this with my (freaky monkey) toes.

So, anyway. My point was this: it’s not particularly unusual weather for March. It’s just really annoying.

What a lot of hot air.

Well that was a resounding disappointment. I hate to begin a post on such a negative note, but frankly, everything is so shrouded in grey cloud at the moment, it was almost inevitable.

I’ve just finished Block 1: Air. Never has such an interesting topic been made so dull, by so few. It was written by people whose skill in communication is limited to “dry and dusty”. I’ve had teachers like that in my time, and it’s thoroughly depressing.

Honestly – I know I’m a massive geek – but it’s global weather systems. It’s not only fascinating, but useful to us all – knowing what the weather is going to do from one day to the next is handy.

And I now understand why predicting short-term weather is so difficult. Long-term weather: not so much.

Although, as previously alluded to, the book is so densely written that I’m going to have to give it another once-over if I’m going to come close to getting a distinction for S216…

The basics are relatively simple – it’s just beginners’ physics. The wind blows across a horizontal pressure gradient, from high to low pressure. The fact that the Earth spins on a tilted axis affects temperatures and wind directions profoundly. Seasons are rather groovy.

I don’t really see why the book needed to preface many of its explanations with “imagine an Earth that does not rotate”. Why? Why would I do that? The Earth does rotate. Don’t go confusing things by explaining something that is irrelevant. Particularly when the concept of the Coriolis Effect is not difficult to grasp.

(The Coriolis Effect, for those who don’t know, is what causes an object to deviate from a straight path. Imagine you’re trying to land a rocket ship on a particular spot on the Earth’s surface. It’s not enough to simply aim for it and shoot; the Earth’s spin means that when you get there, the spot you were aiming for will have moved. Make sense? Or, imagine you’re firing some kind of a deadly weapon from the North Pole straight down a line of longitude to That London. Unless you correct for the Coriolis Effect, your missile will drift off to the west and end up somewhere in the Atlantic Ocean. The Earth spins through around 15° of latitude in an hour, so after one hour it would be 15° off course.)

It reminds me of an old friend, who had a physics lecturer who once began a lesson with the immortal words: “Assume a cylindrical duck”. At least that little gem has provided amusement over the years…

Anyway. The aspect of Air that i found most interesting was the El Niño Southern Oscillation (ENSO). El Niño is Spanish for “little boy”, and is so called because the event occurs every year around Christmas time. The name relates specifically to the birth of Jesus. At the end of each year, a warm current invades the coastal waters off Peru and Ecuador, warming the sea for a few weeks before the cold currents return.

But once or twice a decade, a much stronger warming effect occurs, which has far-reaching consequences for far-flung places. It lasts for several months and can lead to very severe flooding in places that do not normally receive a lot of rainfall – the normally arid coastal regions of Peru and Ecuador.

It is linked to a similar warming across the central and eastern equatorial Pacific Ocean, as well as a link between the warming and a large-scale, pan-tropical-Pacific variation in the mean sea-level pressure.

The high pressure over the tropical Pacific, and the low over Australia and much of Indonesia, can change gradually, with the high weakening (decreasing in pressure) and the low filling (increasing in pressure). The horizontal pressure gradient decreases dramatically, causing the Trade Winds to weaken or even reverse in direction.

This, in turn, causes the warm water to migrate slowly eastwards across the Pacific – and this patch of anomalously warm water is followed by cumulonimbus clouds formed by the surface heating. The clouds bring torrential rain to Pacific island groups that normally don’t get that wet.

The clouds are extremely tall, pushing a lot of heat into the upper troposphere, which strengthens the jet streams and extends them eastwards. Which is how El Niño can have such dramatic effects far outside its usual arena.

Although the event is not predictable in the sense that it occurs every two to seven years, there is plenty of warning that it will occur. Our understanding of how this works enables experts to put plans in place to deal with unusual weather, lessening the impact of droughts in some places and floods in others.

El Niño was one of the few sections of Air that was reasonably well explained. Such a shame that the rest of the book was overcomplicated, self-indulgent rambling. Speaking of self-indulgent rambling, I really hope that the rest of the course improves. It’s going to be extremely hard going if not.

All this was compounded by the fact that I only got 75% for TMA01. This was partly due to some silly and careless errors by me, and partly because the Open University is continuing its policy of cloudy and impenetrable question styles. I’m going to have to pull my socks up if I want a distinction. I have a feeling it’s going to be considerably more difficult than S104.

Sex on two wheels

Positive thinking will return. I’m sure of it. It’ll start on Friday lunchtime when I test ride the 2012 Triumph Street Triple. Oh, did I mention that I’m buying a brand new motorbike? It’ll help, honestly. Because four wheels move the body, but two wheels move the soul.

Pseudo-philosophical and navel gazing rambles aside, it’s at moments like these you need to step back and say: “Where’s the bloody knife party?”

I wandered lonely as a cloud…

I know it’s not the done thing to diss the Romantic poets, but I’m not sure clouds are really lonely, are they? Let’s anthropomorphise them for a moment, and consider the evidence in a logical and scientific manner.

Cumulus

Cumulus clouds. They don't look lonely.

Cumulus is a lumpy cloud. Its name comes from the Latin for “mass” or “heap”. It’s a good description; a lumpy heap of cloud.

It has clearly-defined edges, and looks like cotton wool. In my head, I can sleep in them because they look so very comfy. And when I’m in aeroplanes, I always think it would be nice to jump out and land in one. In fact, it is the type of cloud drawn expertly by children everywhere, and can be found moonlighting as Father Christmas’s beard as and when required. A cloud such as this could not possibly be lonely.

Interesting fact about cumulus clouds: they form “streets” when they get together. And have street parties because they are harbingers of good weather; they don’t generally grow tall, and so do not participate in precipitation.

Stratocumulus

Stratocumulus cloud. A cumulus with a hangover.

Stratocumulus is a “flattened lump or heap”. So, basically, it’s a cumulus cloud with a hangover. It doesn’t get high, forming in the lowest two kilometres of the atmosphere and, like it’s more portly brethren, is not associated with precipitation.

I suppose an argument could be made for this cloud being lonely, but I would take issue with that. It has formed from a squishy mass of cumulus clouds, which is pretty neighbourly, and chose its own hungover state. It’s usually found in the company of others, which makes it fairly sociable.

Arguably, this cloud is not lonely either. Also, it indicates high pressure and stable winter weather. So it is a pleasant fellow.

Cirrostratus

Cirrostratus. Wispy. Friendly.

So named from the Latin cirrus, “wisp” or “curl”, and stratus, “layer”. A wispy layer of cloud. They spend their time high up in the atmosphere (between five and ten kilometres) as a veritable veil of ice crystals.

Cirrostratus halo. Spooky.

They often produce a halo effect (see photo) and indicate moist air and an approaching warm front. Cirrostratus and altostratus form from each other. Such close relationships indicate that cirrostratus are unlikely to be lonely clouds. Quite the opposite, in fact.

Cirrus

These wisps are the aloof clouds of the cloud world. They form in the highest and coldest regions of the trophosphere, are composed of ice crystals, do not bring rain, and they spawned Will ‘o’ the Wisp, Kenneth Williams’ alter ego and entertainer of children of the 80s.

There is a variety of different cirrus clouds – cirrostratus, described above, is just one type. Others include cirrus intortus, tools of the Spanish Inquisition. Nobody expects the Spanish Inquisition to use clouds as instruments of torture. Cirrus castellanus is another type of cirrus cloud, used to build castles in the sky; and cirrus vertebratus has no backbone.

Cirrus clouds can be artificial too; contrails from aeroplanes are a type of cirrus cloud. You can judge wind direction up there by looking at how contrails are scattered. And if they persist, you know the relative humidity is quite high. If they disappear quickly, the air up there is very dry. So they’re useful things too.

But they all join with each other, and with other cloud types, and are most definitely not lonely.

Nimbostratus

Nimbostratus. Lonely, perhaps, but not wandering.

These are low-lying clouds that bring rain. They are named from the Latin “nimbus”, meaning rain, and “stratus”, meaning spread-out. They are big, with flat bases, and are often to be found engulfing the top of a hill. Of course, from the hill’s point of view this stratus cloud would be fog. They are the bullies of the cloud world, being big grey brooding miseries, and are the friends of the hills.

They produce dull and gloomy wet days, with the cloud base often touching the ground. The word “fug” describes them nicely.

I suppose that these clouds could be described as lonely. But they don’t wander, so my original point stands.

Anyway.

As part of Block 2: Air and Earth, we are studying weather systems. This is, sadly, not as interesting as I thought it might be. I think the extreme weather comes in later in the course. For now, the only thing that has held my interest is the clouds.

I love clouds. They bring depth and mood to the sky, and can often be found making interesting shapes – like pigs, and teapots, and – on the odd occasion – snakes and slippers.

They can also give you a clue as to what the weather may do next, if you know what you’re looking for. So this post was really for my benefit; to make sure I’ve got a vague idea of what clouds look like, and what they herald weather-wise.

I still think cumulus clouds would make a grand bed though. The laws of physics and common senses be damned.

Cool scientific instruments

Of these, there are many; this much is true. However, by far the coolest scientific instrument I have seen recently is this: the sunshine hours recorder.

Coolest scientific instrument of the day

I came across this during my virtual fieldtrip to the Teign Valley, where I am having a crash course in climate in the local area. We’re trundling around a meteorological station and poking about in the instrumentation.

This device is a thing of beauty. It’s a crystal ball, for goodness’ sake. What’s not to like? And it is simplicity itself. The glass ball focuses sunlight onto the paper chart, and burns a small hole in it. When the sun is behind a cloud, no hole is burned.

Useful things don’t have to be ugly. Here endeth today’s (very short) lesson. I’m off to get me a crystal ball.