The effect of volcanic activity on the world’s weather, though well known and documented, remains the subject of intense study. Part of this is in response to the on-going concerns relating to global warming, and how changes in atmospheric components, volcanic or otherwise, can drive climate. But major volcanic events are sporadic and tough to predict, increasingly forcing scientists to look back in time, piecing together the circumstances surrounding eruptions far more cataclysmic than anything experienced in our own short recorded history. In these titanic events, researchers can see the potentially catastrophic interplay of weather and geology.
And of all the volcanic events that are known to have taken place in the last 500 million years, none is believed to have had a bigger impact on the climate, and the life forms it supported, than the so-called Siberian Traps event. Occurring about 250 million years ago, before even the time of the dinosaurs, the Siberian Traps event is not really a single short-term geological occurrence. Rather, it was a massive and continuous expulsion of lava over a long period of time, perhaps a million years, that ultimately resulted in the greatest single extinction of life ever known to have taken place, the Permian-Triassic extinction. It’s strength was not only in its size, but in the fact that it just kept going, almost knocking out the planet’s thin coating of life.
First, a description of the almost unimaginable volcanic activity itself. It is believed by some to have been so massive because of its unusual source. That source is thought to have been what is called a mantle plume, an uncommonly huge upwelling of superheated rock from deep within the earth’s mantle, far deeper and larger than the heat source of most volcanoes that owe their energy to plate tectonics. (Some have speculated that mantle plumes could be the source of the hot-spots blamed for super volcanoes.)
According to the theory, when a large mantle plume broke through the earth’s crust 250 million years ago, the result was a vast and extended eruption from many volcanic vents, incessantly spewing oceans of lava over what is now northern Siberia. (Some have even suggested an asteroid impact as the initiator of the eruptions.) To get an idea of the total amount of lava ultimately ejected, imagine the entire surface of the earth covered by nearly 10 feet of lava. The lava, as it turned out, did not spread over the entire earth. Instead, it continually cooled, building up on itself and limiting its final size to an area roughly that of Western Europe, two miles thick in places.
But it was the unparalleled effect on Permian life of this environmental catastrophe that marks its significance. At first, the increasing lava flows caused a gradual change in the environment that put mounting pressure on surrounding life forms. Volcanic ash from explosive eruptions could have initially blocked the sun’s rays, cooling the planet. Gradually, however, the release of carbon dioxide and other gases generated other pressures, including global warming and ongoing acid rains. Dying plant life would have impacted animal life and oxygenation on the land and in the seas. As time went on, the oceans themselves began to warm significantly. Ocean levels would rise and ocean currents could shut down, further aggravating weather extremes. As the oceans continued to heat, methane gas hydrates started to thaw, releasing enormous amounts of methane gas into the atmosphere. Methane is a greenhouse gas many times more powerful than carbon dioxide, and would have greatly accelerated the warming process. The combination of extremes was simply too much for the majority of plants and animals.
The volcanic activity eventually stopped, but it was too late. In the end, over 90% of all species on earth were wiped out. Even insects, almost never connected with mass extinctions, were broadly hit. The loss in biodiversity was so great that it took tens of millions of years for life to get back to a level close to what it had been before the event.
Will such an event ever happen again? Today there are still hotspots that carry with them the potential of massive volcanic events able to change weather and threaten large segments of animal and plant populations. Perhaps the most famous is that underlying Yellowstone National Park in Wyoming. Its biggest eruption was 2.2 million years ago when it covered much of North America with ash, and unleashed over 2,000 cubic kilometers of lava, changing weather and threatening plant and animal life. But the Siberian Traps event is in a league of its own and may never be matched. Think of Yellowstone, and then multiply the volume by 1,000.
For more information, visit http://www.allyknowsweather.com/.
Sunday, June 27, 2010
Sunday, May 23, 2010
Ice Bombs – The Weather Mystery
There is perhaps no weather phenomenon more bizarre, less understood, or under-reported, than the ice bomb. In fact, it is unclear just how related to weather it even is.
What is an ice bomb? Sometimes called a megacryometeor, an ice bomb is basically a large chunk of ice falling out of the sky. By large, think perhaps 2-50 pounds, sometimes much more; something that can blast a hole in your roof several feet in diameter; something the size of a basketball or far larger, and that could, traveling at well over 100 miles per hour, damage or destroy anything (or anyone) it hits.
If you’re thinking about hail, think again. Although hailstones can indeed grow to be dangerously large, ice bombs are far larger, and often fall when the sky is perfectly clear, with no storms or even clouds anywhere near.
Ice bombs have been reported all over the world and, in spite of their relative rarity, homes and vehicles have been severely damaged, and a few people have been injured or killed. Of course, if nobody is there to witness such an event, the ice would simply melt away and leave no trace unless something was visibly damaged. So we don’t know exactly how rare it really is. It can be months between reports, but ice bombs can also occur in clusters, with multiple events happening within the space of a week or two, and within a few hundred miles of one another.
One suggestion, not unexpected, is that ice bombs could be the result of chunks of ice falling off of high flying airplanes. After all, in the U.S. alone, thousands of commercial and military aircraft typically fill the daytime and nighttime sky in virtually every part of the country. Some think it could come from ice buildup that can form on the wings, or even wastewater from malfunctioning systems within the planes. Although the FAA downplays the possibility, the issue of ice falling from planes is still the subject of heated discussion.
However, there are ice bomb events that the airplane theory simply doesn’t explain. Some events, for example, occurred prior to the invention of the airplane, with reports going back to at least the mid 1800s. In addition, some ice bombs are simply too huge, some as big as a car, to be explained by ice buildup on airplanes. Plus, in those cases where ice has been recovered and analyzed, results indicate that it does not have the characteristics of airplane wastewater.
Some people have suggested the possibility of small comets. But, in order for ice to survive the fiery dive into our atmosphere at high speeds, the chunks would have to be quite large, and would have been spotted visually or on radar, which has not been the case. And suggestions that ice bombs could be the result of unusual events in the upper stratosphere are difficult to accept, due to the lack of moisture and supporting air at such high altitudes. Moreover, some analytical results point to a tropospheric origin, the lower portion of the atmosphere below 50,000 feet.
So the search for an answer to one of weather’s most puzzling events goes on. Although we can take some comfort in the realization that the odds of ever being hit by an ice bomb are indeed astronomical, we are all forced to accept the possibility that there could be a 100 pound chunk of ice out there somewhere with our name on it.
For more information, visit www.AllyKnowsWeather.com.
What is an ice bomb? Sometimes called a megacryometeor, an ice bomb is basically a large chunk of ice falling out of the sky. By large, think perhaps 2-50 pounds, sometimes much more; something that can blast a hole in your roof several feet in diameter; something the size of a basketball or far larger, and that could, traveling at well over 100 miles per hour, damage or destroy anything (or anyone) it hits.
If you’re thinking about hail, think again. Although hailstones can indeed grow to be dangerously large, ice bombs are far larger, and often fall when the sky is perfectly clear, with no storms or even clouds anywhere near.
Ice bombs have been reported all over the world and, in spite of their relative rarity, homes and vehicles have been severely damaged, and a few people have been injured or killed. Of course, if nobody is there to witness such an event, the ice would simply melt away and leave no trace unless something was visibly damaged. So we don’t know exactly how rare it really is. It can be months between reports, but ice bombs can also occur in clusters, with multiple events happening within the space of a week or two, and within a few hundred miles of one another.
One suggestion, not unexpected, is that ice bombs could be the result of chunks of ice falling off of high flying airplanes. After all, in the U.S. alone, thousands of commercial and military aircraft typically fill the daytime and nighttime sky in virtually every part of the country. Some think it could come from ice buildup that can form on the wings, or even wastewater from malfunctioning systems within the planes. Although the FAA downplays the possibility, the issue of ice falling from planes is still the subject of heated discussion.
However, there are ice bomb events that the airplane theory simply doesn’t explain. Some events, for example, occurred prior to the invention of the airplane, with reports going back to at least the mid 1800s. In addition, some ice bombs are simply too huge, some as big as a car, to be explained by ice buildup on airplanes. Plus, in those cases where ice has been recovered and analyzed, results indicate that it does not have the characteristics of airplane wastewater.
Some people have suggested the possibility of small comets. But, in order for ice to survive the fiery dive into our atmosphere at high speeds, the chunks would have to be quite large, and would have been spotted visually or on radar, which has not been the case. And suggestions that ice bombs could be the result of unusual events in the upper stratosphere are difficult to accept, due to the lack of moisture and supporting air at such high altitudes. Moreover, some analytical results point to a tropospheric origin, the lower portion of the atmosphere below 50,000 feet.
So the search for an answer to one of weather’s most puzzling events goes on. Although we can take some comfort in the realization that the odds of ever being hit by an ice bomb are indeed astronomical, we are all forced to accept the possibility that there could be a 100 pound chunk of ice out there somewhere with our name on it.
For more information, visit www.AllyKnowsWeather.com.
Wednesday, May 19, 2010
Methane Hydrates, A Weather Timebomb?
The fire that destroyed the British Petroleum operated oil platform in the Gulf of Mexico, ultimately resulting in a massive release of oil into the Gulf, has once again put a spotlight on one of the biggest questions associated with weather, and specifically with the possible consequences of warming oceans. The question is about methane hydrates, and what effect increasing ocean temperatures could have on their stability, and on the possible release of vast amounts of methane, an extraordinarily powerful greenhouse gas, into the atmosphere.
That explosive BP fire may, some feel, have been triggered by methane from methane hydrates, an icy substance composed of methane and other gases frozen in a mixture at the bottom of the sea. Heat generated by cement being used to seal the well is thought to be the source of energy that warmed the hydrates, releasing the gas. The gas, it is suggested, then burst upward and ignited, starting a fire that eventually brought down the entire platform.
The dramatic set of events in the Gulf gave a hint of the potential power and risks posed by the warming of methane hydrates, found in many parts of the world’s oceans. Any significant warming of the ocean could allow the release of huge amounts of methane, the combustible nature of which is only a part of the problem. The more serious fact is that methane is one of the most effective greenhouse gases known, perhaps 10-20 times more potent than carbon dioxide.
Some researchers believe that a release of gas from methane hydrates 55 million years ago was responsible for turning an initial warming into a runaway overheating of the earth, resulting in a large scale extinction, primarily of large or aquatic animals and plants.
The heating created a world that was remarkably different than our own. Neither the north or south pole regions would have had any ice, the temperature of the arctic ocean could have approached a balmy 70° F. While organisms in many parts of world faced extinction, Antarctica would have become lush and green. As atmospheric temperatures around the world rose by approximately 10° F, and ice melted, sea levels rose. Evaporation increased, putting more moisture into the air, which often fell out near the poles, reducing the density of the saltwater there. Ocean circulation changed, accelerating ocean warming. The effects were rapid enough that many life forms failed to adapt.
Eventually, life was able to adjust and then recover, though only after more than 100,000 years, and is thought by some to itself be a key factor in the eventual reduction in global temperatures.
Given all this, it’s little wonder that scientists looking at the BP accident are interested in more than just the effect of oil leakage. It gives them a disquieting opportunity to learn more about what could be a ticking timebomb for the world’s weather.
That explosive BP fire may, some feel, have been triggered by methane from methane hydrates, an icy substance composed of methane and other gases frozen in a mixture at the bottom of the sea. Heat generated by cement being used to seal the well is thought to be the source of energy that warmed the hydrates, releasing the gas. The gas, it is suggested, then burst upward and ignited, starting a fire that eventually brought down the entire platform.
The dramatic set of events in the Gulf gave a hint of the potential power and risks posed by the warming of methane hydrates, found in many parts of the world’s oceans. Any significant warming of the ocean could allow the release of huge amounts of methane, the combustible nature of which is only a part of the problem. The more serious fact is that methane is one of the most effective greenhouse gases known, perhaps 10-20 times more potent than carbon dioxide.
Some researchers believe that a release of gas from methane hydrates 55 million years ago was responsible for turning an initial warming into a runaway overheating of the earth, resulting in a large scale extinction, primarily of large or aquatic animals and plants.
The heating created a world that was remarkably different than our own. Neither the north or south pole regions would have had any ice, the temperature of the arctic ocean could have approached a balmy 70° F. While organisms in many parts of world faced extinction, Antarctica would have become lush and green. As atmospheric temperatures around the world rose by approximately 10° F, and ice melted, sea levels rose. Evaporation increased, putting more moisture into the air, which often fell out near the poles, reducing the density of the saltwater there. Ocean circulation changed, accelerating ocean warming. The effects were rapid enough that many life forms failed to adapt.
Eventually, life was able to adjust and then recover, though only after more than 100,000 years, and is thought by some to itself be a key factor in the eventual reduction in global temperatures.
Given all this, it’s little wonder that scientists looking at the BP accident are interested in more than just the effect of oil leakage. It gives them a disquieting opportunity to learn more about what could be a ticking timebomb for the world’s weather.
For more information, visit www.AllyKnowsWeather.com.
What You Don’t Know About Tornadoes
In the United States, every spring and summer brings tornadoes, one of the world’s most spectacular and least understood weather events. The U.S. gets more tornadoes than anyplace on earth, usually over 1,000 annually, largely in the south central states, with Texas, Oklahoma, and Kansas getting the most violent hits. But you may not know that every state, including Alaska and Hawaii, has experienced tornadoes, and that west central Florida has an especially high concentration of tornadoes, though Florida’s twisters are generally weaker and short lived.
In addition, tornadoes vary widely in size and strength. Most tornadoes are only a few hundred feet across, but some have been known to be over 2 miles wide. Most have wind speeds of less than 100 miles per hour, but Oklahoma City experienced a tornado in 1999 with wind speeds measured at 318 miles per hour, a world record. Most tornadoes are on the ground for just a few minutes before dissipating, while some are confirmed to have lasted for over an hour.
But the most significant thing we don’t know about tornadoes is exactly how they form. It’s not enough to talk about the convergence of warm moist air with cool air and dry air, because those conditions occur all the time in the central U.S., and many other places, without resulting in a tornado. And most thunderstorms, the incubator for all tornados, live their life without spawning anything close to a tornado.
Tornadoes are more commonly believed to be the product of particular smaller scale events that take place within a storm cell, but there is still disagreement about exactly what those events are. One of the problems, of course, is that it’s impossible to set up shop inside a tornado to take detailed measurements. Tornadoes occur sporadically, and instrumentation that can survive such violent conditions is not easily deployed.
Forecasters have had decades of experience dealing with tornadoes, improvements in radar now help researchers accurately track wind patterns, and computer modeling even allows a certain amount of experimentation, and yet it’s still impossible to predict the detailed formation of a tornado much in advance. The variables are simply too many, and are not well enough understood.
So, with every tornado season, people throughout much of the United States can do little but look up at the darkening skys and wonder.
In addition, tornadoes vary widely in size and strength. Most tornadoes are only a few hundred feet across, but some have been known to be over 2 miles wide. Most have wind speeds of less than 100 miles per hour, but Oklahoma City experienced a tornado in 1999 with wind speeds measured at 318 miles per hour, a world record. Most tornadoes are on the ground for just a few minutes before dissipating, while some are confirmed to have lasted for over an hour.
But the most significant thing we don’t know about tornadoes is exactly how they form. It’s not enough to talk about the convergence of warm moist air with cool air and dry air, because those conditions occur all the time in the central U.S., and many other places, without resulting in a tornado. And most thunderstorms, the incubator for all tornados, live their life without spawning anything close to a tornado.
Tornadoes are more commonly believed to be the product of particular smaller scale events that take place within a storm cell, but there is still disagreement about exactly what those events are. One of the problems, of course, is that it’s impossible to set up shop inside a tornado to take detailed measurements. Tornadoes occur sporadically, and instrumentation that can survive such violent conditions is not easily deployed.
Forecasters have had decades of experience dealing with tornadoes, improvements in radar now help researchers accurately track wind patterns, and computer modeling even allows a certain amount of experimentation, and yet it’s still impossible to predict the detailed formation of a tornado much in advance. The variables are simply too many, and are not well enough understood.
So, with every tornado season, people throughout much of the United States can do little but look up at the darkening skys and wonder.
For more information, visit www.AllyKnowsWeather.com.
(Photo shown is courtesy of the NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory - NSSL)
(Photo shown is courtesy of the NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory - NSSL)
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