Tag Archive: Great Courses

Oceanography: Exploring Earth’s Final Wilderness

It’s been almost 50 years since I took an oceanography course, so I ordered this course as a refresher. It was a refresher all right, and not just of what I remembered of oceanography — this course covers everything from the history of the Earth to modern-day pollution. As one of my old colleagues at the Geophysical Institute says, “It’s not Planet Earth, it’s planet Cloud-Ocean.”  And this course was a marvelous refresher of the whole of geophysics, core to tropopause, and some biology with the whole thing straightforward enough to be understandable to almost anyone.

It started out conventionally enough, with an overview of the history of oceanic exploration. But many of the observations of the ocean basins demanded explanation. Why did the mid-Atlantic ridge exist, for instance? The Challenger Deep? For that matter, why were island arcs so often paralleled by trenches and home to volcanoes and earthquakes? What were the magnetic stripes discovered during World War II? How was it that the sea floor, which should have been receiving sediments from the continents throughout geologic history, had astonishingly young bedrock when drills began to penetrate those sediments? Some of these questions were touched on 50 years ago, some were hastily swept under the rug, and some (such as the puzzlingly young age of the seafloor bedrock) had not even been discovered yet.

These questions eventually led to the theory of plate tectonics, and several lectures on these DVDs are devoted to explaining this theory and how it came about. But that’s a small part of the first two discs in this set of six.

The physics and chemistry of water take up several lectures. Waves, rogue waves, tsunamis, and tides are covered, along with some of the physics of water. For something so familiar (oxygen and hydrogen are two of the most common reactive elements in the universe) water has some astonishing properties. Not only does it have an extraordinarily high heat capacity and is it very nearly the universal solvent, it is one of the few compounds in which the solid phase is less dense than the liquid. In other words, ice floats! We’re so used to this we don’t even think about it, but the world would be very different if ice sank, as most solids do in their own melts.

Life in the seas is interesting in itself and also critical to feeding our global population. Food webs, plankton, jellyfish, fish, marine mammals and birds and whales all get their moments of exposure, along with fish farming.

Then the course moves on to coasts: estuaries, deltas, beaches and sea cliffs. Life is here, too, from sea grasses and mangroves to coral reefs.

The lectures then cover storms, the deep ocean circulation, and the effects of climate change and pollution.

As a meteorologist I would of course like to have seen more on the role of the oceans in influencing weather. Not only are the oceans the great flywheel of climate, and their slow response one of the problems in climate modeling, they provide much of the water vapor that transports energy around the globe. Still, 36 half hour lectures can’t cover everything. Professor Tobin certainly tried, though, and for a single course succeeded brilliantly.

Every now and then I order a course on DVDs from The Great Courses. Most recently, I’ve been viewing Skywatching, a course by Alex Fippenkio on the sky, day and night: what can be seen in it and the physics of why it looks the way it does.

Roughly the first third of the course deals with what we can see in the daytime sky. Dr. Filippenko discusses sky color in midday and when the sun is rising or setting, clouds, lightning, and the interaction of sunlight with water and ice (giving rainbows and halos.) This is closely related to what I researched and taught, so I didn’t really lean anything new. The presentation, however, was generally good. I did catch an error in one diagram, but I suspect that was the graphic designer. (The diagram is the one used to explain polarization in reflected light, and the error is that the angle of reflection and the angle of incidence are not shown as equal.) I was also rather disappointed that Dr Filippenko did not point out that frozen droplets are initially near-spherical, and develop their hexagonal prism shape (and the optical effects this produces) only later, by vapor-phase growth. But I suppose I shouldn’t expect everyone to be familiar with ice fog.

This section of the course should be of particular interest to writers needing information on sky and cloud cover, storms, and less common phenomena such as rainbows or sundogs. If you are going to describe an evening sky, you’d better have some idea of what’s happening.

Roughly half the course deals with the constellations and observing the bodies of the solar system. Most of this I was familiar with as an amateur, and I’ve used some of it — lunar phases and seasons, for instance — in my writing. Every writer who wants to put a moon in the sky should watch the section on lunar phases. Rising crescent moon in the evening? Nope. Just doesn’t happen. Neither does a narrow crescent high in the sky.

The lecture on solar eclipses brought back the one I saw, shortly after I moved to Alaska in 1963. I didn’t have a car yet, but two other graduate students gave me a ride down to Sourdough, Alaska to see the total solar eclipse of July 20, 1963. There were scattered high clouds, and while they added suspense –would the sky be clear during totality? – they wound up adding to the experience. Every bright spot of Bailey’s Beads had its own rainbow (technically iridescence.) I know I took a picture; I remember taking photos both before and after the eclipse, the ones after being a series with the exposure set at a constant value to capture the change in the light. I found that series, but so far the ones before and during totality are missing. They may have been separate from the others and lost during the fire twelve years ago.

Overall I’d give the course an A. Dr. Filippenko is a wonderful teacher, and with few exceptions the graphics are excellent. The course takes 3 DVDs and consists of 12 45-minute lectures.