Storm chasers know that puffy cumulus clouds often cause sudden rainstorms, while storms associated with stratus clouds form more slowly. Now physicists at England’s Open University have finally found an explanation.
They propose that neighboring water droplets in a stable stratus cloud don’t crash into each other because they’re all moving at about the same speed. But fast-forming, turbulent cumulous clouds contain water droplets moving at many different speeds. They crash into each other and form larger drops. As the turbulence grows, the drops grow quickly and fall as rain within a few minutes.
Sun and rain
Ever noticed the bright, moving lines on the bottom of a stream, bathtub, or swimming pool? They’re called caustics, and they’re caused when ripples on the water’s surface focus sunlight. (Caustics form whenever light rays are bent by a curved surface or object and then projected onto another surface.
Caustics have a characteristic shape. Physicists can graph the phenomenon mathematically, and the graph also describes other phenomena, such as particle motion or the movement of raindrops within a cumulus cloud.
Atmosphere to outer space
The researchers say their finding won’t have any impact on weather forecasting. But particle collisions in turbulent gases must have been involved in planet formation. Perhaps the same theory can be applied?
If you're at the museum on Saturday afternoon (11/18), the MakeIt team can help you play with caustics. Does bending mylar in a different direction produce a new pattern? Does using a different color flashlight or a brighter or dimmer light affect the design?
You can also play with caustics at home.
Physicist Kenneth Libbrecht used a high-resolution microscope to take pictures of snowflakes. These images were put on to four new 39-cent commemorative stamps by the United States Postal Service. The images were taken from snowflakes in Michigan, Alaska, and Ontario. To take the picture, Libbrecht used a paintbrush to transfer the snowflake onto a glass slide. He then took the picture using a digital camera through a high-resolution microscope. Libbrecht does most of his work outside to keep the snowflakes from melting. According to Libbrecht, there are 35 different types of snowflake crystals. The stamps feature two specific types, stellar dendrite snowflake crystals and sectored plate snowflake crystals.
Snowflakes are created when a water droplet inside a cloud freezes into an ice particle. The particle spreads out and becomes a six-sided prism as water vapor gathers on its surface. As more vapor accumulates, the prism grows branches and begins to look like a crystal. No two snowflakes are the same because, inside the cloud, the snowflake crystal is pushed around between temperature and humidity changes which affect the shape of the snowflake.
R. Buckminster Fuller's 1969 book imagines humanity as a crew aboard a tiny spaceship traveling through infinity. We have limited water, food, and fuel. Because of our proximity to the sun, we are given a limited budget of additional fuel which allows growth of food, trees, and fish. The sun's energy input also cycles our water and air. We even have past energy from the sun stored up in the form of coal and oil.
What happens if we use up more food and energy each year than the Earth/Sun system can regenerate? Each year Global Footprint Network calculates humanity’s Ecological Footprint (its demand on cropland, pasture, forests and fisheries) and compares it with global biocapacity (the ability of these ecosystems to generate resources and absorb wastes). They declared that today (Oct. 9th) is Global Overshoot Day, the day we passed our biocapacity limit.
"We are clearly drawing natural capital ... the point about collapse is that we don't know when some of the systems in the global atmosphere and fish will collapse but we do know that collapse is a very real possibility" says Professor Tim Jackson, head of sustainable development at Surrey University via The Independent)
We are living beyond our means. Earth's six billion inhabitants and their rising living standards are putting an intolerable strain on nature.
The biggest problem relating to the over-consumption of resources is climate change, but its other effects include deforestation, falling agricultural yields and overfishing.
Overfishing should be easy to understand. If you harvest fish with nets faster than they can reproduce, pretty soon there are not enough fish. Remember what happened at Red Lake.
Global Footprint Network is committed to fostering a world where all people have the opportunity to live satisfying lives within the means of Earth's ecological capacity. You can read about their accomplishments and publications here.
Human records of hurricanes go back less than 100 years. Can we somehow look at nature's record of weather within tree rings?
The moisture carried by hurricanes carries a different ratio of oxygen-18 to oxygen-16 than the normal rain that trees absorb. When that moisture falls near a tree, it is absorbed, and that ratio of oxygen is reflected in that year's ring.
Comparing the tree-ring data to the National Weather Service data over a 50-year period, the tree-ring data showed only one year in which their data reported a hurricane that was not in the list of recorded storms. Tennessee Today
Two University of Tennessee professors, Claudia Mora and Henri Grissino-Mayer, noted that this opens the door for research to go back even further than 220 years, as older trees are discovered in hurricane-prone areas, perhaps as old as 500 years.
Too bad bristlecone pines don't grow in the hurricane zones. The tree ring record in bristcones go back over 7000 years. Dendrochrology is the dating of past events (climatic changes) through study of tree ring growth. If you want to look tree rings of various trees, come to Collections Gallery at the Science Museum of Minnesota. We have one tree slice with 522 rings.
There's been a rash of cool weather sites written up in the Twin Cities newspapers and other media lately.
Here are just a few:
Skeetobiteweather is one of the most popular hurricane sites run by amateurs. Jonathon Grant, of Lakeland, Florida, runs it. He says the site gets 1.8 million page views a week, and you can plug in your zip code and get a prediction of wind forces for your block, hour-by-hour, before a hurricane hits. (Not even the National Weather Service does that.) And pretty soon, you'll be able to enter your exact address.
Mark Sudduth, of Wilmington, North Carolina, runs HurricaneTrack and HurricaneLiveNet. He deploys several battery-powered, waterproof cameras at the exact points where hurricanes are expected to hit. He also collects weather data to accompany the live, streaming video.
Jesse Bass, of Hampton Roads, Virginia, is a weather chaser who posts photos and commentary on his website, VAStormPhoto.
HurricaneCity, despite its name, is one of the more comprehensive severe weather sites. Jim Williams, of Delray Beach, Florida, focuses on the city being hit, and you can see all live, streaming radio stations or TV from the site. He also has a towercam on his roof, which captured images from Hurricane Wilma last year, and he hosts "The Hurricane Warning Show" from his living room.
Mike Watkins, of Coconut Creek, Florida, covers Atlantic hurricane action on TropicalUpdate. And if there's no news on the hurricane front, he hosts an Internet radio show where he interviews the "celebrities" of the weather world--guys like Max Mayfield, of the National Hurricane Center, or William Gray, the Colorado State University professor who's known for his hurricane season forecasts.
Greenhouse gases that have been trapped in frozen permafrost are being released from the melting soil much faster than was previously thought. The most notable one of these gases is methane, which is being released into the atmosphere at a rate 5 times greater than was previously thought.
Methane is an effective heat trapping agent, it is 23 times more powerful at trapping heat in the atmosphere than carbon dioxide. It is practically harmless when it is frozen in permafrost.
Permafrost is ground that has consistently been at a temperature of zero degrees Celsius (32 degrees Fahrenheit) for two or more years. Permafrost occurs in regions of Arctic climates, such as the tundra of Alaska, northern Canada, and Siberia. Unfortunately, when these frozen climates get too warm, the trapped atmospheric gases are released. Unfortunately, this is now happening too frequently due to global warming.
The release of methane from melting permafrost speeds up the global warming process. The current warming of the earth causes the permafrost to melt, which causes methane and carbon dioxide to be released into the atmosphere, which causes more warming. It’s a horrible cycle and scientists are worried that it will eventually go out of control, setting off a “climate time bomb.”
Scientists are unsure whether or not methane or carbon dioxide is the worst greenhouse gas. While methane traps more heat, it only lingers in the atmosphere for around 10 years. Carbon dioxide traps less heat, but it typically remains in the atmosphere for a century. Neither of these gases is good.
Sounds like quite the problem. What do you think we can do about it?
Did you know that you can insist that the amount of electricity you use be produced without generating carbon dioxide emissions or other forms of pollution (mercury, sulfer). Windsource electricity is produced without air emissions, such as carbon dioxide and sulfur dioxide, both considered to contribute to greenhouse gases. Wind-generated electricity also uses no water and therefore requires no water treatment during production. I am doing this by joining the Windsource program.
Xcel Energy will be held accountable for using Windsource funds appropriately: it must file annual reports with the Minnesota Department of Commerce and Minnesota Public Utilities Commission, accounting for program revenues and expenses and wind generation and sales. In addition, all wind facilities supplying the Windsource program will be certified by the Minnesota Department of Commerce. Sierraclub
I have agreed to pay $2 per 100 kWh extra on my electric bill. This month I used 304 kWh so I was billed an extra $6.08. Since my electricity is pollution free I was rebated the Fuel Cost Adjustment that I otherwise would have paid ($2.76). So I paid an extra $3.32 last month know that I am helping rather than hurting our future environment. When fuel cost rise enough the rebate can become greater than what you pay for Windsource. You can sign up for Windsource here or call 1-800-895-4999 anytime.
And that could speed up global warming with 'incalculable consequences', says alarming new research. Studies by the blue-chip Woods Hole Research Centre, carried out in Amazonia, have concluded that the forest cannot withstand more than two consecutive years of drought without breaking down. And that process, which would be irreversible, could begin as early as next year.
For those who'd like some perspective, the Amazon rainforest represents half the rainforests in the world. It encompasses 1.2 billion acres, or 1.875 million square miles. That's 3.25% of the planets land mass. That’s a huge chunk of land. So if this report is accurate, it’s far from being insignificant.
The Amazon now appears to be entering its second successive year of drought, raising the possibility that it could start dying next year. The immense forest contains 90 billion tons of carbon, enough in itself to increase the rate of global warming by 50 per cent.
Read more from The Independent (U.K.), July 23, 2006
First noticed in 2002, the dead zone is larger this year than in previous years.
What is a dead zone? It's an large area of water that's very low in oxygen and can't support life. (Scientists call this "hypoxia.") Dead zones are caused by the explosive growth of tiny aquatic plants called phytoplankton. When the phytoplankton die, they are decomposed by bacteria. Massive numbers of bacteria use up the oxygen in the water. Any animals that can swim out of the low-oxygen water--like many fish--do so. Others--some fish, many crabs, and others--suffocate because they can't get enough oxygen to live.
In this case, the phytoplankton blooms are caused when north winds cause upwelling in the water column. The cooler water is rich in nutrients, providing a feast for the phytoplankton. When the wind dies down, the upwelling stops, and many phytoplankton die a natural death. Their decomposition results in water that is deadly because it lacks oxygen needed for life.
This year, the upwelling started in April, stopped in May, and started up again in June. The off-and-on upwelling creates a thick mat of organic material that rots and uses up the oxygen in the water. Then, when a new upwelling occurs, the oxygen-depleted water moves toward shore, killing the plants and animals that can't get out of its way.
So, why the upwelling? Jane Lubchenco, professor of marine ecology at Oregon State University and a member of the Pew Oceans Commission, told the Associated Press:
"We are seeing wild swings from year to year in the timing and duration of the winds that are favorable for upwelling. ... This increased variability in the winds is consistent with what we would expect under climate change."
Global warming is also the suspect in dead zones off Namibia, South Africa, and Peru.
(The dead zone in the Gulf of Mexico at the mouth of the Mississippi River is caused by agricultural runoff containing fertilizers. The river carries all those nutrients into the Gulf, creating algal blooms that use up all the oxygen.)
Have you been following the comments in Cari's Buzz Blog post about Gore's movie, An Inconvenient Truth. I find it interesting that very intelligent people can look at the same data ("truths") and yet totally disagree as to what to accept as reality?
George Musser on the Scientific American Blog has been moderating a discussion about global warming titled Are You a Global Warming Skeptic? Part IV He started the discussion March 6, 2006 with this statement:
In the comments field, explain which aspects of climate change you don't accept (e.g. you might not think Earth is warming at all, you might not think the warming is due to greenhouse gases, you might not think that the gases are produced by humans, or you might not think warming will cause trouble in the future), what exactly has led you to this conclusion, and -- most important -- what it would take to convince you otherwise. Let's get everything out into the open, so that we can have a real discussion.
The discussion is presented in four parts with hundreds of comments. I am recommending this thread because Musser first listens to, then presents a summary of the skeptics' arguments. I find the fairest way to make up my mind on an issue is to thoroughly understand both sides of the argument. Musser explains how scientists crunch the various data to answer difficult questions. He uses the analogy of examining fingerprints during a crime scene investigation.
Climatologists have maps and time series showing how a boatload of climate variables -- mean temperature, temperature ranges, air pressure, precipitation, and so on -- vary in time and in space, horizontally across the surface and vertically through the atmosphere. These data sets are a gold mine for resolving ambiguity, because the different forcings leave distinct fingerprints. Such patterns make it possible to tease out their relative contributions. Over the years, researchers have considered ever more variables besides temperature and ever more forcings besides greenhouse gases. They have merged spatial and temporal patterns, looked at regional as well as global scales, and developed more sophisticated mathematical tools.
"Fingerprints" included solar variability, volcanic eruptions, greenhouse gasses, ozone, aeosols, and various generic effects. When climatologists run the fingerprinting analysis for different historical epochs, they find that temperature fluctuations prior to the Industrial Revolution were driven primarily by solar and volcanic forcings. In the early 20th century, natural and anthropogenic forcings seem to contribute equally. From midcentury onwards, greenhouse gases rule(temporal pattern). Since 1979, when continuous satellites observations began, the surface and troposphere have warmed and the stratosphere has cooled(vertical pattern). Pretty much the entire surface has gotten warmer, high latitudes more than lower ones(horizontal pattern). All the oceans have warmed; there isn't the zero-sum game of warming and cooling you'd expect from natural variability(energy variability).
"unless I'm missing something, it seems to me that the case for anthropogenic warming is pretty strong...Based on the knowledge we have so far, however, I have to call 'em as I see 'em."
To appreciate the use of critical thinking and scientific method I recommend wading through the four installments of "Are you a global warming skeptic?" Part I (673 words); Part II (2219 words); Part III (2617 words); Part IV (3516 words); and an Appendix