Saturday, September 21, 2013

Terra Nova Cognita

Planet Earth never ceases to surprise us. Within the past month we've discovered a canyon and a volcano, both of which are longer and larger than the previous record-holders in those categories.

The first record-breaker, known as the Greenland Grand Canyon, remained unknown until last month because it lies beneath Greenland's ice cap. It was discovered using ice-penetrating radar and is over 750 kilometers (466 miles) long, a bit less than twice the length of the Grand Canyon in Arizona (at 446 kilometers [277 miles] long. It's also up to 800 meters (2,600 feet) deep, and up to 10 kilometers (6 miles) wide. (Though Arizona's Grand Canyon is both deeper and wider in places.)

(The longest canyon in the world is actually the Yarlung Tsangpo Grand Canyon in Tibet, which is a bit longer than the Grand Canyon in Arizona, although I couldn't find solid numbers on how much longer. It is also the worlds deepest canyon, with a deepest point of 6,009 meters [19,714 feet].)

The second record-breaker is a volcano located on the Pacific sea floor about one-third of the way from Japan to Hawai'i. This humongous edifice goes by the name of Tamu Massif, and while it has been known since at least 1993, it was previously thought to be multiple volcanoes due to its incredible size. On it September 5th it was announced by scientists studying it that it was actually a single volcano, which made it the largest volcano on earth.

This announcement was of interest to me, since I live on the flank of what was previously thought to be the largest volcano in the world – Mauna Loa. When we say “largest,” we should be sure to define what we mean. Tamu Massif is larger in surface area than Mauna Loa, but shorter in height. Mauna Loa has a surface area of 5,000 square kilometers (about 1,900 square miles), and rises an incredible 9,170 meters from the sea floor (30,085 feet). Tamu Massif, by contrast, rises a mere 4,460 meters (14,620 feet) from the sea floor, but has a surface area of 260,000 square kilometers (100,000 square miles), approximately the size of New Mexico.

Despite its height, the summit of Tamu Massif is still 1,980 meters (6,500 feet) below the surface of the Pacific Ocean. This is because it has an incredibly gentle slope (it's also long extinct, so it's not getting any higher). Mauna Loa has slopes that don't exceed an average inclination of 12 degrees, but Tamus Massif's sides have an average inclination of no more than a single degree.

Tamu Massif has some interesting similarities with a volcano on Mars called Alba Mons. Since “Everything's Bigger on Mars” when it comes to geological features, it's no surprise that Alba Mons is larger than Tamu Massif. In terms of surface area it stretches for a good 1,000 by 1,500 kilometers (620 by 930 miles). Like Tamu Massif, it too has incredibly gentle slopes of 0.5 degrees on average.

It's not surprising that these incredible features of our world could remain hidden for so long, given their locations under ice cap and ocean. It's definitely exciting that we're starting to discover them. Who knows what else there is out there waiting to be discovered? A hui hou!

Monday, September 9, 2013

Science Clock Series: Part XII

This little series is finally drawing to a close with today's number, which comes from meteorology, and is given by:

\[\text{hurricane (Beaufort scale)}\] This is another straightforward number from the realm of atmospheric science. The Beaufort scale (officially the "Beaufort wind force scale") is a system devised by a certain Sir Francis Beaufort in 1805 as a way to standardize the reporting of wind speeds by ships and weather centers.

Wind speed can be fairly subjective – one person's "stiff breeze" might be another's "light wind," for instance – and it was long recognized that a standardized system for measuring wind speed would be a good thing. Beaufort wasn't the first to work on such a scale, but his position in the British Royal Navy in the 1830s allowed him to get his officially adopted.

The Beaufort scale has twelve categories, going from 1 (completely calm) to 12 (hurricane force winds). The categories were originally defined by the effects they produced (on the ocean, on ships' sails, or on various terrestrial objects), due to the difficulty in measuring the wind speed directly. Once practical, reliable anemometers (wind-speed measuring devices) became widespread, the different categories became defined by specific wind speeds as well.

Beaufort originally defined the scale to go up to 12, but in 1946 an extended scale was proposed going all the way up to 16. The wind speeds in this range are pretty much only encountered in tropical cyclones, and the extension only ever caught on in Taiwan and China, both of which deal with tropical cyclones on a frequent basis.

I'd reproduce the Beaufort scale table in this post, but unlike the Mohs scale of mineral hardness, it's pretty long and involved. If you're interested, I suggest perusing it on Wikipedia at the link just above.

And with that, this series is officially over. It was an interesting experience; I learned some things myself, both about the subjects in question and in running a series of posts. I apologize for the tardiness with which I've been updating lately; I sometimes found that having a set subject to post about next left me undermotivated.

Anyway, it's over now, and I have a couple of new post ideas in mind. What will come next? You'll just have to wait and see. A hui hou!