These days any weather report worth its salt will include the UV index number. I think we all understand the practicality of it. The higher the number, the higher risk of sunburn. But personally, that superficial understanding doesn’t satisfy my curiosity.

I also get to brag a little, as the UV Index in a Canadian invention, circa 1992. Many other countries picked up on the idea. It’s now been taken over and standardized by the World Health Organization.

We’re talking about ultraviolet radiation here, which got a mention last week regarding its spot on the spectrum of electromagnetic waves. There are three types of UV radiation, conveniently called UVA, UVB, and UVC depending on the wavelength. Each one affects us differently.

UVA: These are the longest waves, and thus can more easily pass through stuff. As such, nearly 99% of all UV radiation that gets through the ozone layer is UVA. UVA causes immediate tanning, and long term wrinkling and skin aging.

UVB: While making up only 2% of ultraviolet radiation reaching earth, this is the bad guy. The cause of skin cancer! Last year I wrote about how a sunburn modifies your genes!

UVC: Our ozone layer pretty much completely blocks UVC radiation from reaching us. Let’s hear it for the ozone, ladies and gentlemen!

Now, the UV index is a rating of how much UV radiation is hitting the earth on a given day.It’s calculated based on a number of factors specific to your area.

1. Sun height – Midday in mid-summer would have the sun looking straight down on you, meaning the least amount of atmosphere between you.
2. Latitude - Your position on the globe affects the angle of the sun.
3. Cloud cover – Well that seems obvious!
4. Altitude – The higher you are, the less atmosphere to protect you. Being 1000 meters above sea level equals a UV increase of about 10%.
5. Ozone – The ozone fluctuates, so it can be absorbing more or less UV on any given day.
6. Ground reflection – Depending on the colour and surface, you could be getting UV bounce-back. Snow will reflect 80% of UV waves.

At night, in the dark, the UV index would be zero. While there’s no upper limit to the scale, 10 would be “extreme”… blue sky, mid summer, sun directly overhead.

I’ll wrap up with a note about sunscreen. Specifically that big SPF number on the bottle. You may know it means Sun Protection Factor. That number is determined with a simple lab test.

They round up some pasty looking people and test how long it takes for their bare skin to burn under a controlled dose of UV light. Then they apply the sunscreen to another patch of skin, and measure the time to burn again. If the original burn happened in 3 minutes, and the sunscreened burn took an hour, that means the natural skin protection increased by a factor of 20. (3 minutes x 20 = 60 minutes) Thus, it gets labeled as Sun Protection Factor 20.

• Source: Ultraviolet Radiation – World Health Organization
• Source: Ultraviolet Index – Wikipedia

P.S. The illustration above was inspired by the random words found in robot-proof captcha security things. (where they ask you to decipher a blurry word… in my case “climate iseight”) Captcha Art is kind of an in thing to do these days. The drawing then reminded me I’ve been wanting to do a story on the UV index for a while.

It’s finally gotten to the point where I can lay out on the grass and stare at the sky without the risk of being covered in snow. Let’s celebrate with the game show craze that’s not exactly sweeping the nation… Name That Cloud! You’ve probably heard the cloud names before, but if you’re like me, you couldn’t accurately match them up with the real thing. (unless you’re thinking of names like “puffy” and “dark”)

Clouds are classified based on their height and structure.

Clouds below 2000 meters are called stratus.The word comes from Latin for “spread out”. The two types of cloud in this category are nimbostratus and stratocumulus. To my untrained eye, there’s not a big difference between the two, but the stratocumulus should be more lumpy and uneven. Both tend to result in those dreary grey days where it’s trying to rain but not particularly succeeding. Sometimes stratus clouds get low enough to touch… what we call fog.

Above 6000 meters are the cirrus clouds. Cirrus in Latin translates to “curl of hair”. These are the wispy clouds that are just thin lines across an otherwise blue sky. Cirrostratus (high-level, spread out) clouds are nearly invisible, as they are a sparse collection of ice crystals that stretch across wide areas. They sometimes hint at their existence by creating a halo effect around the sun or moon.

Between those two levels, clouds get dubbed “alto”. Either altrostratus or altocumulus. Altostratus (remember “spread out”) is what we call overcast. It’s a light grey covers that dulls the sun, but rarely makes for any rain. Filmmakers love this! Altocumulus clouds show up like ripples across the sky, not unlike the sandy bottom of a lake, and may foretell a coming thunderstorm.

Cumulus clouds, named from Latin for “pile up” (like accumulate), are the stereotypical fluffy cotton-ball clouds. They come and go with a lifespan of 5 to 40 minutes. Everybody loves cumulus clouds. But you do have to watch out for the evil Dr. Jekyll version called cumulonimbus. These are the gigantic, huge, towering clouds that bring powerful storms.

This all should make perfect sense… if you can speak Latin. For the rest of us, here’s the quick memonic guide to souding really smart about clouds.

Spread-out… straddling the sky… Stratus

Fluffy… piled-up… accumulated… Cumulus

Wispy… seriously thin… Cirrus (okay, that one’s a stretch, I admit)

And for those of you who can’t get enough cloud facts, many months ago I wrote a article to calculate how much a cloud weighs. (hint: it’s seriously heavy!)

• Source: Cloud classifications from the University of Illinois

It’s Groundhog Day. For those of us in cooler climates, this gets a lot of attention. Personally, I’m not a fan, but I won’t let that get between you and the facts. So, he says with a fake cheer that could rival any TV weatherman, what’s up with this crazy Groundhog Day tradition?

The gist of it is that a groundhog, an animal that sleeps all winter, is supposed to poke it’s head out the door and from whether or not it sees its own shadow, we can determine that warm weather is on the way… or not. First of all, a groundhogs have never shown any particular meteorological inclinations… they were just the convenient hibernating mammal of choice. Now even I would make an effort to tune in the weather report for “Grizzly Bear Day”.

This whole thing is based on the fact that February 2nd falls precisely in the middle between Winter Solstice (first day of winter) and Vernal Equinox (first day of spring). An ancient religious ceremony that came to America with German settlers is responsible for the weather predicting element.

Called Candlemas, it was believed that the weather on this day would predict the rest of winter. If it was nice and warm, then it was a calm between winter storms, and spring would be late. If today has crummy weather, then the idea is that winter will get tired without a break, and spring arrives early.

That directly translates to Groundhog day as a warm sunny day means that Punxsutawney Phil (America’s foremost weatherhog) will cast a strong shadow that’s hard to miss… thus “early spring”. With poor weather, the cold dreary overcast of Pennsylvania means no shadow, and more winter. Basically, the groundhog here serves no more useful purpose than that of a stick.

Perhaps the most interesting part of the whole thing is that in a 50/50 situation Phil’s prediction record of the last century is quite poor at 39% accuracy. That suggests he’s actually trying to be wrong. That’s what you get for trusting a groundhog.

• Source: The Origin of Groundhog Day – Hubpages

Yesterday I mentioned that if you were standing at the equator you’d be spinning around the earth at about 1600 km/h. You, personally, are probably moving slower than that. Perhaps much slower.

The further north (or south) you go in the world, the slower the rotation speed. If you were standing exactly at the true north pole, and you stayed there all day (wearing thick underwear I hope), you would get yourself turned around with the earth but you would not really go anywhere. Your speed would be zero km/h. If you walked ten meters away from the north pole, and stood there all day, you would spin around a path 62.8 meters long, moving at a speed of 0.03 km/h.

The closer you are to the equator, the fatter the earth gets, the further you have to travel to spin around once, and the faster you go. I’m in Calgary, on the same latitude as London, so in both cities we are spinning at about 1050 km/h. That’s 550 km/h slower than equatorial folk. Hold that thought.

If you were driving along the street in a car at 50 km/h, and saw your friend walking in the same direction on the sidewalk at 5 km/h, you might feel inclined to throw a hamburger to him. At the moment you pass him, you throw that hamburger straight at him, and not to brag, but you have perfect aim. The problem is inertia. You, your car, and that hamburger are all moving at 50 km/h, and during its flight the hamburger continues to move at 50 km/h, while the intended recipient is still walking at 5 km/h. End result: the hamburger lands in front of your sad hungry friend. Hold that thought.

People at the equator are “driving” at 1600 km/h. People in Calgary and London are “walking” at 1050 km/h. Superman is in Brazil, and he throws me a hamburger. (only Superman could) While in flight the hamburger continues to travel east at its original 1600 km/h speed and Calgary doesn’t keep up. End result: the hamburger lands further east than it was originally aiming for.

This is called the Coriolis effect. It’s what makes our weather patterns work the way they do. Wind moving north will curve to the right. Wind moving south will curve to the left. This is what causes hurricanes to spin, and what creates the the major circular ocean currents.

At this point some of you might be thinking about Australian toilets. The Coriolis effect is often cited as causing toilets in the north to drain counter-clockwise, while toilets in the southern hemisphere drain with a clockwise spin. The concept is true, but in a practical sense the Coriolis effect is only noticed over large distances. The spin of your toilet bowl will mostly be influenced by the more immediate effects like the angle at which the water is pumped in.

• Source: http://stratus.ssec.wisc.edu/courses/gg101/coriolis/coriolis.html

This post is part of “Blog Action Day“, wherein over 7000 blogs will be posting on the topic of climate change. The goal is to raise awareness of the issues and concerns of the global environment. I have a hunch that my post is not quite what they had in mind.

I’ll come right out and say it: I am not at all worried about global warming. I don’t believe it’s a crisis, or even a concern. The current state of fear and sense of impending doom has been nurtured by the media, who are just trying to sell newspapers. I don’t deny that the global temperatures are rising, but it’s not a problem. Here’s some hype-free facts about climate change…

The leading cause of global warming is the sun. The giver of all life. Obviously, it has the biggest impact on everything here on earth. Like most humongous balls of burning gas, it’s not a static thing. It moves, it changes. A scientific paper form March 2008 determined that 62% of temperature change has been the result of the sun, caused by short-term fluctuations and long-term solar cycles.

The earth also has it’s cycles. In the time of the dinosaurs, carbon dioxide levels were 2 to 4 times higher than they are now, but things have cooled off a few times since then. About 125,000 years ago, at the peak before the most recent ice age, global temperatures were much higher, and the sea level was 20 feet above current levels. Still, things froze up yet again.

We only really started keeping track of temperatures around 1850. Studies of Greenland ice cores, which offer a timeline of weather going back a few millenia, indicate that the northern hemisphere circa mid 1800s was the coldest period in about 8,000 years. So the average temperatures would have nowhere to go but up. The point being, rising temperatures are not a crisis. We’re just on a natural upswing.

In 2007 all the world heard reports about the University of Illinois study revealing that Arctic ice was at it’s lowest levels in 30 years. Nobody seemed to mention the bit in the same study that mentioned the Antarctic ice down south was at record highs.

I don’t understand why people love doom and gloom news stories so much, but I do hope I’ve encouraged you to take a peek beyond the hype. There are some serious environmental concerns we should be dealing with rather than fretting about the multi-millennial ebb and flow of climate cycles.

• Source: http://www.climatechangefacts.info/ (This is a massive resource of scientific research presented plainly. You don’t have to take my word for it.)

Well here I go, taking something that’s all purdy and majestic and reducing it to plain old math and facts. The sunset, with all it’s glorious splendour, is caused by less than splendourous dust. Plain old dust hanging around the air.

It’s the way that the particles cause the radiating light to scatter, as explained by the mathematic Mie solution, that creates the multiple layers of colour. It’s the same thing going on when you shine a light through a prism and the white light seperates into our good buddy Roy G. Biv. (see also: Pink Floyd album covers) Due to the steep angle, the sun’s rays have to pass through more dust and air particles before you see it, causing the distortion.

The sunset is more vividly coloured than the sunrise because morning air is generally not as calm, so there are less suspended particles. Also,  sunsets can be made more dramatic due to forest fires or volcanic eruptions adding more soot to the air. So general rule of thumb, the more you enjoy the sunset, the more you’ll be stuffed up in the morning.

There’s also a nifty little phenomenon cleverly called green flash, which is a brief, er, “flash” of green that can be spotted at the very tippy top of a setting sun. This effect usually can only be seen for a second or two near the end of a sunset.

• Read about it in the book “SurelyYou’re Joking Mr. Feynman” http://lsned.com/books/feynman
• Online Source: http://en.wikipedia.org/wiki/Sunset

This may well be the fluffiest fact I’ve ever published, since there is no definitive answer. Clouds can vary widely in size, shape, and density but this answer is straight from the mouth of a genuine scientist, so there you go. (note: that should be read as ‘gen-yoooo-ine scientist‘ for proper effect) However, it would be more accurate for me to say…

FACT: An average cloud, of average size, and average water density, roughly, approximately, pretty much weighs about 4 million killograms, give or take, more or less.

…but that doesn’t fit on Twitter.

In order to put that into scope, that everyday-joe fluffy cloud weighs as much as 37 fully grown blue whales. (or 2 million flowerpots) So for goodness sakes, when Chicken Little suggests the sky might be falling… RUN!

• Source: http://www.newton.dep.anl.gov/newton/askasci/1993/general/GEN012.HTM