Do You Know What a Dangerous 'Internal Wave' is in the Air or the Ocean?

From Denny: This was new to me. What the heck is an 'internal wave' and why is it important to know about this phenomenon? It's one of those hidden dangers the public isn't aware of when they fly or take an ocean cruise.

These things can get huge, like 1,000 kilometers wide. They can have a tremendous impact upon our Earth's climate and are prevalent in both the oceans and the atmosphere. What they can adversely affect are oil drilling rigs out in the oceans, undersea communications cables, submarines and aircraft in flight.

A recent example of sudden danger that went undetected from radar or a talented pilot was what happened to a Canadian flight in clear skies last year. For absolutely no apparent reason the plane plummeted 2,000 feet in a mere 15 seconds and then an additional 2,000 feet before the pilot was able to right the plane and level off. Passengers and crew were terrified with 10 passengers requiring hospital treatment for injuries.

For the past five years there's been a mechanical engineering professor over at MIT that has been studying this scary phenomenon that can sneak up on us and cause acute damage quickly. This professor, Thomas Peacock, has been figuring out how internal waves form and propagate. For the high brow scientist crowd you can find his latest papers published in a few months in the Journal of Fluid Mechanics.

What do his papers cover? The first one discusses the forms of internal waves that are generated in the oceans. The second one talks about a mystery in a channel of the Hawaiian Islands. Tied to the tides there is something that occurs twice a day here on a regular basis: a focused beam of internal waves. What's peculiar is that the internal wave occurs in the channel yet vanishes as it progresses near the ocean surface.

Researchers want to understand these internal waves to help create better models for climate change. They believe that these internal waves in the ocean are important to the mixing process of carrying warmer surface water to the deep and bringing colder water to the surface. Internal waves are one of the ocean mechanisms that strongly impact Earth's climate. This oceanic mixing rate is the least understood and if studied further could go a long way to creating more accurate climate projections.

So, what is it that bedevils these researchers about internal waves? They have come a long way toward understanding how internal waves are produced. Their next step is figuring out how their energy dissipates. Right now they can account for 20% of the wave "break" but the remaining 80% is still a mystery.

Because there are practical applications for his research, Thomas Peacock has drawn some heavy weight investors, providing funding to aid him in his study: the National Science Foundation, the MIT France Program and the Office of Naval Research.

How do internal waves form in the ocean? One way is when tidal currents pass over a submerged ocean ridge that acts as an obstacle, setting up a disturbance. Powerful storms like hurricanes can produce them too by displacing the ocean surface.

How do internal waves form in the atmosphere? Thunderstorms passing over a mountain range can cause them as in the case of the Canadian flight that was terrified in the example stated above. Those internal waves are label 'mountain waves.'

To help us understand this phenomena better the Discovery Channel has been working on a film with professor Thomas Peacock. They have been filming in Western Australia and the South China Sea. Guess what they will be chasing in the hopes they can film it? It's called a Morning Glory cloud which is a long, narrow cylindrical cloud formation that can span up to hundreds of miles.

Peacock and the film crew hope to 'surf' that cloud in a glider since this is the time of year most conducive to this kind of cloud phenomenon. Like Peacock says, "It's a challenge, to try to be there when it happens," he says. "But it will be a once-in-a-lifetime experience to surf the Morning Glory." Sounds like an extreme sport!

Science: Earth Gets Billion-Year Life Extension

From Denny: It seems like every few years scientists decide the Earth is really an older planet and, oh, by the way, they think the sun will exist for a few million or so years longer. Not to worry, folks, we will still have a home for mankind for a little while longer! :) Here's the latest from Wired.com's Wired Science blog.

"The Earth could be habitable for another 2.3 billion years, extending previous estimates of life’s horizon by more than 1 billion years.

King Fai Li and his colleagues at Caltech hypothesize that Earth’s atmospheric pressure has always varied, and that it could fall in the distant future, keeping Earth from frying for far longer than previous research had shown.

If the new idea proves correct and can be extended to other planets with biospheres, it could increase the chances that earthly civilization finds extraterrestrial life by doubling the percentage of time that planets could be inhabited.

“[T]he Earth will be identifiable as an inhabited planet for nearly half the total lifetime of the Sun, an important point to consider in the search for life on extrasolar planets,” the authors write in the Proceedings of the National Academy of Sciences.

Over the next hundreds of millions of years, the sun will continue to get brighter until eventually, Earth becomes too hot to inhabit. Previous calculations had pegged that time at about a billion years from now, but the new paper argues that earlier models had neglected the role of atmospheric pressure in regulating the temperature of the planet on astronomical time scales.

Atmospheric pressure is a key variable in the overall greenhouse-gas effect because it determines how much infrared radiation greenhouse gases absorb. Higher pressures mean more absorption and consequently, more heat. Lower pressures have the opposite effect.

Life itself would be the mechanism for these temperature changes. By “fixing” nitrogen, pulling it out of the air and eventually into the Earth’s deep ocean, microbes could be making the atmosphere lighter one atom at a time.

“I am glad that Li and colleagues have raised the issue of how overall variation in atmospheric pressure may have affected past and may affect future climate,” ecologist Ken Caldeira of Stanford University said in an e-mail. “This could be relevant for understanding climate change on the billion-year time scale.”"

For the continuation of this article just click on the title link.

Science: Sun Induces Strange ‘Breathing’ of Earth’s Atmosphere

From Denny: Seems like I'm still getting caught up on what's going on in our solar system, published in December 2008. This was a fascinating article about something I had never given thought: there is a rhythmic contraction and expansion of the Earth's atmosphere in relation to the sun. I find it interesting that the scientist being interviewed has the last name of Solomon, after the wisest man ever to walk the Earth. Read on from Wired.com's Wired Science blog:

NASA Seal Image via Wikipedia

"SAN FRANCISCO — New satellite observations have revealed a previously unknown rhythmic expansion and contraction of Earth’s atmosphere on a nine-day cycle.

This "breathing" corresponds to changes in the sun’s magnetic fields as it completes rotations once every 27 days, NASA and University of Colorado, Boulder, scientists said Monday at the American Geophysical Union annual meeting.

The sun’s coronal holes, seen as dark regions in the image above, direct plasma away from the sun and out into the solar system. When these particles get to the Earth, they heat the upper atmosphere, causing the outer atmosphere to expand and contract.

"What’s going on in the solar side is indeed mysterious and challenges the solar physics understanding," said Stan Solomon, a scientist at the National Center for Atmospheric Research who was not involved in the research.

The finding emphasizes the many ways that solar activity impacts the Earth — and its increasingly space-utilizing humans.

"From the Earth’s perspective, we’re in the sun’s outer atmosphere," said Jeffrey Thayer, an aerospace engineer at UC-Boulder.

The new discovery could help scientists and engineers design better satellites that account for the changing conditions in the ionosphere. Eventually, it might be possible to predict the severity of ionospheric storms and protect the world’s communication infrastructure.

The scientists used changes in the density of the Earth’s atmosphere to pinpoint this previously unknown pattern. As the atmosphere contracts or expands, it also gets more or less dense, respectively. In response to the "hills and valleys of density," satellites subtly speed up or slow down, recording those motions with on-board accelerometers. And that’s the data that allowed the scientists to back into the discovery of this new atmospheric cycle.

Solomon said that while the cycle on Earth is interesting, the really strange aspect of this work is what it says about our local star.

"What’s going on in the sun that’s causing all this?" Solomon said. "It’s not entirely clear. That part of it is quite mysterious.""

Astronomy: The eta Aquarid Meteor Shower

Alpha Monocerotid meteor shower in 1995. Perseid meteor shower, richest shower of the year, peaks in August. Image via Wikipedia

From Denny: You will want to get out of bed early come Wednesday morning to see the meteor showers! You can have your coffee later.

SpaceWeather.com is reporting:

Forecasters expect the 2009 eta Aquarid shower to peak on Wednesday morning, May 6th, with as many as 85 meteors per hour over the southern hemisphere. Sky watchers in Australia, New Zealand, South America and southern Africa are favored. Rates in the northern hemisphere will be less, 20 to 30 per hour. The best time to look is during the moonless hour before local sunrise. That is when the shower's radiant is high in the sky and the nearly-full Moon will have set, leaving the sky dark for meteors.




Sky Map for the Northern Hemisphere

Eta Aquarids are flakes of dust from Halley's Comet, which last visited Earth in 1986. Although the comet is now far away, beyond the orbit of Uranus, it left behind a stream of dust. Earth passes through the stream twice a year in May and October. In May we have the eta Aquarid meteor shower, in October the Orionids. Both are caused by Halley's Comet.

The shower is named after a 4th-magnitude star in the constellation Aquarius. The star has nothing to do with the meteor shower except that, coincidentally, meteors appear to emerge from a point nearby. Eta Aquarii is 156 light years from Earth and 44 times more luminous than the Sun.

The constellation Aquarius does not rise very far above the horizon in the northern hemisphere, and that's why northerners see relatively few meteors. But the ones they do see could be spectacular Earthgrazers.



Sky Map for Southern Hemisphere

Earthgrazers are meteors that skim horizontally through the upper atmosphere. They are slow and dramatic, streaking far across the sky. The best time to look for Earthgrazers is between 2:00 to 2:30 a.m. local time when Aquarius is just peeking above the horizon.

Experienced meteor watchers suggest the following viewing strategy: Dress warmly. Bring a reclining chair, or spread a thick blanket over a flat spot of ground. Lie down and look up somewhat toward the east. Meteors can appear in any part of the sky, although their trails will point back toward Aquarius.

Tidbits:

Eta Aquarid meteoroids hit Earth's atmosphere traveling 66 km/s.

Typical eta Aquarid meteors are as bright as a 3rd magnitude star.

Weather: Hurricane-Killing, Space-Based Power Plant

From Denny: Since I live in the hurricane zone and a lot of America is now increasingly experiencing the same, well, this article sure caught my eye from Wired.com. It seems the sci-fi of what used to be our scary future has now arrived on our doorstep. It is a little disconcerting to start tinkering with Mother Nature as you never really know how she will respond to our meddling.



Here's an excerpt:

"How's this for crazy?: A company files a patent to destroy hurricanes as they form by beaming them with energy from a space-based solar plant.

Maybe it is crazy, but that same company, Solaren, took a first step in that direction this week when it inked a deal with the northern California utility, PG&E, to provide 200 megawatts of power capacity transmitted from orbit in 2016.

Apparently, sending up billions of dollars worth of solar collectors and using microwaves to send the energy onto two square miles of receivers in the desert is a little ho-hum to Solaren's wild minds.

"The present invention relates to space-based power systems and, more particularly, to altering weather elements, such as hurricanes or forming hurricanes, using energy generated by a space-based power system," Jim Rogers and Gary Spirnak write in their 2006 patent application.

By heating up the upper and middle levels of an infant hurricane, they say they could disrupt the flows of air that power the enormous storms. Air warmed by tropical waters flows up through a hurricane and is vented through the eye into the upper atmosphere. Theoretically, you could heat up the top of the storm and lower the pressure differential between layers, resulting in a weaker storm."

For a lot more in this article just click on the title link.