Tornado at Union City, Oklahoma Credit: NOAA Photo Library
Also known as a twister, a tornado is a rotating column of air that can cause a tremendous amount of damage on the ground. Tornadoes can very in size from harmless dust devils to devastating twisters with wind speeds greater than 450 km/h.
A tornado looks like a swirling funnel of cloud that stretches from bottom of the clouds down to the ground. Depending on the power of the tornado, there might be a swirling cloud of debris down at the ground, where it’s tearing stuff up. Some tornadoes can look like thin white ropes that stretch from the sky down to the ground, and only destroy a thin patch of ground. Others can be very wide, as much as 4 km across, and leave a trail of destruction for hundreds of kilometers.
Tornadoes appear out of special thunderstorms known as supercells. They contain a region of organized rotation in the atmosphere a few kilometers across. Rainfall within the storm can drag down an area of this rotating atmosphere, to bring it closer to the ground. As it approaches the ground, conservation of momentum causes the wind speed to increase until it’s rotating quickly – this is when tornadoes cause the most damage. After a while the tornado’s source of warm air is choked off, and it dissipates.
When a tornado forms over water, it’s called a waterspout. These can be quite common in the Florida Keys and the northern Adriatic Sea. Most are harmless, like dust devils, but powerful waterspouts can be driven by thunderstorms and be quite dangerous.
Scientists have several scales for measuring the strength and speed of tornadoes. The most well known is the Fujita scale, which ranks tornadoes by the amount of damage they do. A F0 tornado damages trees, but that’s about it, while the most powerful F5 tornado can tear buildings off their foundations. Another scale is known as the TORRO scale, which ranges from T0 to T11. In the United States, 80% of tornadoes are F0, and only 1% are the more violent F4 or F5 twisters.
Although they can form anywhere in the world, tornadoes are mostly found in North America, in a region called Tornado Alley. The United States has the most tornadoes of any country in the world; 4 times as many as the entire continent of Europe. The country gets about 1,200 tornadoes a year.
We have written many articles about the tornado for Universe Today. Here’s an article about the biggest tornado, and here’s an article about how tornadoes are formed.
Wildfires in Russia as seen from space by ESA's Envisat satellite. Credit: ESA
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Massive rains in Pakistan, China and Iowa in the US. Drought, heat and unprecedented fires in Russia and western Canada. 2010 is going down as the year of crazy, extreme weather. Is this just a wacky year or a trend of things to come? According to meteorologists, unusual holding patterns in the jet stream in the northern hemisphere are to blame for the extreme weather in Pakistan and Russia. But also, the World Meteorological Organization and other scientists say this type of weather fits patterns predicted by climate scientists, and could be the result of climate change.
“All these things are the kinds of things we would expect to happen as the planet warms up,” said Tom Wagner, a NASA scientist who studies the cryosphere, during an interview on CNN on August 11. “And we are seeing that the planet is warming about .35 degrees per decade. Places like Greenland are warming even faster, like 3.5 degrees per decade. And all these events from heat waves to stronger monsoons, to loss of ice are all consistent with that. Where it gets a little tricky is assigning any specific event to say, the cause of this event is definitely global warming, that is where we get to the edge of the research.”
“This weather is very unusual but there are always extremes every year,” said Andrew Watson from the University of East Anglia’s Environmental Studies. “We can never say that weather in a single year is unequivocal evidence of climate change, if you get many years of extreme weather then that can point to climate change.”
The Intergovernmental Panel on Climate Change (IPCC) has long predicted that rising global temperatures would produce more frequent and intense heat waves, and more severe rainfalls. In its 2007 report, the panel said these trends have already been observed, with an increase in heat waves since 1950, for example.
NOAA measurements show that the combined global surface temperatures for June 2010 are the warmest on record, and Wagner said there are larger conclusions to be drawn from the definite global warming trend. “We are seeing things that haven’t really happened before on the planet, like warming at this specific rate. We think it is very well tied to increasing carbon dioxide in the atmosphere since the late 1800’s caused by humans.”
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Source: NOAA)
“Not just over 10 years, but we have satellites images, weather station records and other good records going back to the late 1800’s that tells us all about how the planet is warming up,” Wagner said. “Not only that but we have evidence from geologic records, ice cores, and sediment cores from ocean cores. All of this feeds together to show us how the planet is changing.”
Asked if the cycle can be reversed, Wagner replied, “That is the million dollar question. One thing we have to think about is that the planet is changing and we have to deal with that. Ice around Antarctica and Greenland is melting. Sea level is rising right now at 3 millimeters a year. If you just extrapolate that to 100 years, it will rise to at least a foot of sea level rise. But there is the possibility it could be more than that. These are the types of things we need to think about and come up with mitigation strategies to deal with them. We’re doing the research to try and nail down these questions a little more tightly to see how much sea level is going to rise, how much temperatures are going to rise and how are weather patterns going to change.”
Reducing emissions is one thing that everyone can do to help protect the planet and the climate, and climate experts have been saying for years that there needs to be sharp cutbacks in emissions of carbon dioxide and other heat-trapping gases that go into the atmosphere from automobiles, power plants, and other fossil fuel-burning industrial and residential sources.
In the news this week was the huge ice chunk coming loose from a Greenland glacier. Not only is this an indication of warming water, but other problems could develop, such as the large ice chunks getting in the way of shipping lanes or heading towards oil rigs. The high temperatures and fires in Russia are affecting big percentage of the world’s wheat production, and could have an effect on our food supply this coming year.
Not only that, but the wildfires have created a noxious soup of air pollution that is affecting life far beyond just the local regions, JPL reports. Among the pollutants created by wildfires is carbon monoxide, a gas that can pose a variety of health risks at ground level. Carbon monoxide is also an ingredient in the production of ground-level ozone, which causes numerous respiratory problems. As the carbon monoxide from these wildfires is lofted into the atmosphere, it becomes caught in the lower bounds of the mid-latitude jet stream, which swiftly transports it around the globe.
Two movies were created using continuously updated data from the “Eyes on the Earth 3-D” feature, also on NASA’s global climate change website. They show three-day running averages of daily measurements of carbon monoxide present at an altitude of 5.5 kilometers (18,000) feet, along with its global transport.
And in case you are wondering, the recent solar flares have nothing to do with the wildfires — as Ian O’Neill from Discovery space deftly points out.
Caption: One frame from an animation of weather patterns around the south pole of Mars. Credit: NASA/JPL-Caltech/MSSS
If you think about it, those hypnotizing patterns of swirling clouds you see in TV weather reports are pretty amazing: satellites let us see what’s happening in the skies all over the world. But these days, that kind of global vision even goes beyond the Earth. The Mars Reconnaissance Orbiter makes daily weather observations of the Red Planet, and mission scientists regularly compile the pictures into movies that are available online. The result is that anyone can follow along as fierce dust storms rage across the plains of Mars, clouds cling to the peaks of towering volcanoes and polar ice advances and retreats.
On board the MRO is a wide-angle camera called the Mars Color Imager (MARCI) that scans the face of Mars in both visible and ultraviolet light. MARCI views Mars from pole to pole, snapping dozens of images every day that are combined into a global map with resolution comparable to weather satellites at home.
This daily weather report helps Mars explorers understand day-to-day events, as well as seasonal and annual changes on the Red Planet. Sometimes the weather watch also gives rover drivers a crucial warning when a storm might be headed in the direction of Spirit or Opportunity.
The weather images can be striking and intriguing. This animation shows the south pole of Mars during a period of about a month earlier this year, when storms raged along the retreating edge of frost in the polar cap. You can see giant, swirling clouds of dust, as well as the changing shape of the cap as it shrinks with the approach of Summer.
Malin Space Science Systems is the firm that built and operates MARCI for NASA’s Jet Propulsion Laboratory. They post weekly movies that show a spinning, global view of the most recent Martian weather. You never know what you’ll see each week, but a careful look often turns up water ice clouds, wind storms or the giant canyon Valles Marineris filled to the brim with dust.
The descriptions that Malin scientists write to accompany each movie are fascinating. They sound both as exotic as a science fiction novel–and as routine as your local weatherman’s report on the evening news. One sample:
“A large dust storm moved south down the Acidalia/Chryse/Xanthe corridor, partially spilling into eastern Valles Marineris at the beginning of the week. From there the storm moved over Thaumasia and Argyre, picking up intensity as it moved into the subtropics of Aonia and Icaria/Daedalia… Dust storms and water-ice clouds also formed in the northern mid-latitudes, with more notable activity occurring over Deuteronilus and Utopia. The increased amount of dust activity on the planet has created a haze that lingers in the atmosphere and has caused skies over both Opportunity and Spirit to be hazy during the past week.”
That’s why Mars fascinates. It’s an alien world that in some ways is tantalizing similar to home.
MARCI will be turned back on in early December after a hiatus of a few months. Previous weather movies are still online.
Lightning strikes close to the launchpad at Kennedy Space Center on August 25, 2009. Credit: NASA, Ben Cooper. Click the image for access to a larger version.
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If you’re wondering why the first launch attempt for space shuttle Discovery was scrubbed early Tuesday morning, here’s your answer. Yikes! But what a gorgeous picture! And of course, the second launch attempt early Wednesday morning was called off when instrumentation for an 8-inch fill and drain valve on the shuttle’s external tank indicated the valve had failed to close. But yesterday, the valve functioned correctly five times during launch pad tests, NASA said. That means NASA will likely go ahead with a launch attempt at 04:22 GMT (12:22 a.m. ET) on Friday. But the anomaly remains unexplained, so it will be up to the mission management team to decide if the shuttle can fly as is, or if engineers need to know more about the issue. The decision won’t be made, however until the MMT meets Thursday afternoon, just hours before the scheduled liftoff time. As the saying goes, there’s a million parts on the shuttle and if only one is not working….
UPDATE: Launch now is targeted for no earlier than 11:59 p.m. Friday, Aug. 28, to allow engineers more time to develop plans for resolving the issue with the valve.
See below for a close-up of the lightning shot, to see how close it actually came to the shuttle.
Lightining strikes close to Discovery on the launchpad on Aug. 25, 2009. Credit: NASA/Ben Cooper. Click image for access to larger version.
Discovery’s 13-day mission will deliver more than 7 tons of supplies, science racks and equipment, as well as additional environmental hardware to sustain six crew members on the International Space Station. The equipment includes a freezer to store research samples, a new sleeping compartment and the COLBERT treadmill. The mission is the 128th in the Space Shuttle Program, the 37th flight of Discovery and the 30th station assembly flight.
