Asteroid Strikes on Mars Spun Out Supersonic Tornadoes that Scoured the Surface

The study of another planet’s surface features can provide a window into its deep past. Take Mars for example, a planet whose surface is a mishmash of features that speak volumes. In addition to ancient volcanoes and alluvial fans that are indications of past geological activity and liquid water once flowing on the surface, there are also the many impact craters that dot its surface.

In some cases, these impact craters have strange bright streaks emanating from them, ones which reach much farther than basic ejecta patterns would allow. According to a new research study by a team from Brown University, these features are the result of large impacts that generated massive plumes. These would have interacted with Mars’ atmosphere, they argue, causing supersonic winds that scoured the surface.

These features were noticed years ago by Professor Peter H. Schultz, a professor of geological science with the Department of Earth, Environmental, and Planetary Sciences (DEEPS) at Brown University. When studying images taken at night by the Mars Odyssey orbiter using its THEMIS instrument, he noticed steaks that only appeared when imaged in the infrared wavelength.

Artist’s conception of the Mars Odyssey spacecraft. Credit: NASA/JPL

These streaks were only visible in IR because it was only at this wavelength that contrasts in heat retention on the surface were visible. Essentially, brighter regions at night indicate surfaces that retain more heat during the day and take longer to cool. As Schultz explained in a Brown University press release, this allowed for features to be discerned that would otherwise not be noticed:

“You couldn’t see these things at all in visible wavelength images, but in the nighttime infrared they’re very bright. Brightness in the infrared indicates blocky surfaces, which retain more heat than surfaces covered by powder and debris. That tells us that something came along and scoured those surfaces bare.”

Along with Stephanie N. Quintana, a graduate student from DEEPS, the two began to consider other explanations that went beyond basic ejecta patterns. As they indicate in their study – which recently appeared in the journal Icarus under the title “Impact-generated winds on Mars” – this consisted of combining geological observations, laboratory impact experiments and computer modeling of impact processes. 

Ultimately, Schultz and Quintana concluded that crater-forming impacts led to vortex-like storms that reached speeds of up to 800 km/h (500 mph) – in other words, the equivalent of an F8 tornado here on Earth. These storms would have scoured the surface and ultimately led to the observed streak patterns. This conclusion was based in part on work Schultz has done in the past at NASA’s Vertical Gun Range.

An infrared image revealing strange bright streaks extending from Santa Fe crater on Mars. Credit: NASA/JPL-Caltech/Arizona State University.

This high-powered cannon, which can fire projectiles at speeds up to 24,000 km/h (15,000 mph), is used to conduct impact experiments. These experiments have shown that during an impact event, vapor plumes travel outwards from the impact point (just above the surface) at incredible speeds. For the sake of their study, Schultz and Quintana scaled the size of the impacts up, to the point where they corresponded to the impact craters on Mars.

The results indicated that the vapor plume speed would be supersonic, and that its interaction with the Martian atmosphere would generate powerful winds. However, the plume and associated winds would not be responsible for the strange streaks themselves. Since they would be travelling just above the surface, they would not be capable of causing the kind of deep scouring that exists in the streaked areas.

Instead, Schultz and Quintana showed that when the plume struck a raised surface feature – like the ridges of a smaller impact crater – it would create more powerful vortices that would then fall to the surface. It is these, according to their study, that are responsible for the scouring patterns they observed. This conclusion was based on the fact that bright streaks were almost always associated with the downward side of a crater rim.

IR images showing the correlation between the streaks and smaller craters that were in place when the larger crater was formed. Credit: NASA/JPL-Caltech/Arizona State University

As Schultz explained, the study of these streaks could prove useful in helping to establish that rate at which erosion and dust deposition occurs on the Martian surface in certain areas:

“Where these vortices encounter the surface, they sweep away the small particles that sit loose on the surface, exposing the bigger blocky material underneath, and that’s what gives us these streaks. We know these formed at the same time as these large craters, and we can date the age of the craters. So now we have a template for looking at erosion.”

In addition, these streaks could reveal additional information about the state of Mars during the time of impacts. For example, Schultz and Quintana noted that the streaks appear to form around craters that are about 20 km (12.4 mi) in diameter, but not always. Their experiments also revealed that the presence of volatile compounds (such as surface or subsurface water ice) would affect the amount of vapor generated by an impact.

In other words, the presence of streaks around some craters and not others could indicate where and when there was water ice on the Martian surface in the past. It has been known for some time that the disappearance of Mars’ atmosphere over the course of several hundred million years also resulted in the loss of its surface water. By being able to put dates to impact events, we might be able to learn more about Mars’ fateful transformation.

The study of these streaks could also be used to differentiate between the impacts of asteroids and comets on Mars – the latter of which would have had higher concentrations of water ice in them. Once again, detailed studies of Mars’ surface features are allowing scientists to construct a more detailed timeline of its evolution, thus determining how and when it became the cold, dry place we know today!

Further Reading: Brown University, Science Direct

 

Swath of Destruction from Deadly Oklahoma Tornado Visible from Space

The tornado that devastated the region around Moore and Newcastle, Oklahoma on May 20, 2013 has been determined to be an EF-5 tornado, the most severe on the enhanced Fujita scale, and has been called one of the most powerful and destructive tornadoes ever recorded. In this new image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite, the scar of destruction on the Oklahoma landscape is clearly visible from space. In this false-color infrared image, red highlights vegetation, and the tornado track appears as a beige strip running west to east across this image; the color reveals the lack of vegetation in the wake of the storm.

According to the National Weather Service, the tornado was on the ground for 39 minutes, ripping across 17 miles (27 kilometers) from 4.4 miles west of Newcastle to 4.8 miles east of Moore. At its peak, the funnel cloud was 1.3 miles (2.1 kilometers) wide and wind speeds reached 210 miles (340 km) per hour. The storm killed at least 24 people, injured 377, and affected nearly 33,000 in some way.

In this image, infrared, red, and green wavelengths of light have been combined to better distinguish between water, vegetation, bare ground, and human developments. Water is blue. Buildings and paved surfaces are blue-gray.

You can also see an interactive satellite map from Google and Digital Globe, showing detail of every building that was damaged or destroyed. Satellite data like this are helping to assist in the recovery and rebuilding of the area. Satellite imagery can provide a systematic approach to aiding, monitoring and evaluating the process.

Source: NASA Earth Observatory

Astonishing Hi-Resolution Satellite Views of the Destruction from the Moore, Oklahoma Tornado

A new satellite map from Google and Digital Globe shows just-released satellite imagery of the damage from the tornado that struck the area of Moore, Oklahoma on May 20, 2013. It’s been called one of the most powerful and destructive tornadoes ever recorded — determined to be an EF5 tornado, the strongest rating for a tornado — and the destruction is heartbreaking. In the screenshot above, you can see how some houses were left undamaged, while others were completely destroyed.

Click on the image above to have access to an interactive map that shows hi-resolution views of the damage, providing details of where the buildings and houses once were. NPR put this map together, using satellite data from Digital Globe, along with property data from City of Oklahoma City, City of Moore, and Cleveland County. Satellite data like this are helping to assist the recovery and rescue teams on the ground.

In the immediate aftermath of a natural catastrophe such as this tornado, the priority is searching for survivors and saving lives.

But longer term recovery — including the rebuilding of infrastructure and amenities such as schools and hospitals — can take decades, and satellite imagery can provide a systematic approach to aiding, monitoring and evaluating this process.

Satellite view of the destructive tornado that passed just south of Oklahoma City. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this image of the storm at 2:40 p.m. local time (19:40 UTC) on May 20, 2013. Credit: NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC.
Satellite view of the destructive tornado that passed just south of Oklahoma City. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this image of the storm at 2:40 p.m. local time (19:40 UTC) on May 20, 2013. Credit: NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC.

See more satellite views from NASA of the storm and aftermath on NASA Goddard’s Flickr page for this tornado.

The Take Part website has a list of organizations that are providing support for the recovery and care of the people affected, if you would like to contribute.

Oklahoma Tornado on May 20, 2013 As Seen from Space

The massive tornado that tore through parts of Oklahoma on My 20, 2013 left a 32 km (20-mile) swath of destruction and death, with winds approaching 320 km/hr (200 mph). The US National Weather Service said the 3 km (2-mile)-wide tornado spent 40 minutes on the ground in the area of Moore, Oklahoma, outside of Oklahoma City, destroying schools, a hospital and hundreds of homes, killing dozens of people. Satellite images and video show how the storm developed.

Below is a video showing satellite imagery from the GOES 13 satellite from May 19-20, 2013. It shows the tornado outbreak and supercell thunderstorms that developed across portions of the Great Plains:

Weather satellites help scientists to observe weather patterns from the unique vantage point of space. This provides the ability to see a larger area of the Earth rather than with conventional radar which does not reveal a true overview of cloud structure and wind patterns.

These satellites can measure many different things, such as in the image below, which looks at water vapor content of the clouds. The satellites operated by NASA and NOAA and are equipped to send back images in infrared and other wavelengths, providing snapshots of things like the water vapor measurements, temperatures, wind patterns, cloud coverage, storm movement and many other readings. This information also helps with the prediction of storms, allowing for warnings for people to seek shelter from potentially destructive weather events.

This screenshot shows a false color view of the water vapor content in the clouds during the tornado outbreak in Oklahoma on May 20, 2013, as seen from NOAA geostationary (GOES) satellites. Click on image to go to current NOAA imagery.
This screenshot shows a false color view of the water vapor content in the clouds during the tornado outbreak in Oklahoma on May 20, 2013, as seen from NOAA geostationary (GOES) satellites. Click on image to go to current NOAA imagery.

The news from Oklahoma is ongoing, and we encourage you to keep current on the latest information from other news sites. But as Phil Plait pointed out, if you are interested in helping the people involved in this tragedy, the Take Part website has a list of organizations that are in the area providing support.

This full-disk view of Earth shows the formation of the Oklahoma tornado, from the Aqua satellite. Credit: NASA Goddard Space Flight Center.
This full-disk view of Earth shows the formation of the Oklahoma tornado, from the Aqua satellite. Credit: NASA Goddard Space Flight Center.

You can see more images from Oklahoma tornado at the NASA Goddard Space Flight Center Flickr page.

Sources: Marshall Space Flight Center Earth Science office, NOAA Satellite Information office, NOAA website, National Weather Service

Stunning Visualization of 56 Years of Tornadoes in the US

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It’s a wonder of nature, baby. Using information from data.gov, tech blogger John Nelson has created this spectacular image of tornado paths in the US over a 56 year period. The graphic categorizes the storms by F-scale with the brighter neon lines representing more violent storms.

Makes you want to hang on to something solid.

Nelson also provided some stats on all the storms in the different categories:

The numbers represent total deaths, total injuries, average miles the storms traveled
F0: 7, 267, 2
F1: 111, 3270, 6.58
F2: 363, 10373, 11.4
F3: 958, 18160, 17.80
F4: 1912, 28427, 28.62
F5: 1013, 11038, 38.87

This provides a new appreciation for the term “suck zone” used in the movie “Twister.

While tornadoes don’t travel in straight lines, Nelson explains that based on the data, the vectors were created using touchdown points and liftoff points.

Nelson said he got the data from this Data.gov page doing a “tornado tracks” search.

See Nelson’s original post.

Fears of Tornado Catastrophes Due to Global Warming Unfounded

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The 2012 tornado season got off to a rousing start. Between February 28th and March 3rd, two deadly storm systems developed in the southern United States. The storms spawned numerous tornadoes that together killed at least 52 people. This kind of extreme tornado activity, so early in the year, has fueled fears that global warming will increase the severity and duration of the tornado season. But, scientific studies show that this is not necessarily to be expected.

Early tornadoes are not unheard of. For example, on February 29 in 1952, two tornadoes caused severe damage in the south-eastern US. But this year, the number of early tornadoes has been much higher. The National Oceanic and Atmospheric Administration reported that in January of 2012, the tornado total was 95, much higher than the 1991–2010 average of 35. And the five-day total for February 28 to March 3 could rank as the highest ever since record-keeping began in 1950, according to meteorologist Dr. Jeff Masters, co-founder of the Weather Underground. With such a record-breaking start, it is not surprising people worry that a more severe 2012 storm season is ahead, and that global warming is to blame.

Tornadoes form when warm and moist air from the Gulf of Mexico meets with very cold and dry air above, which was brought south from the arctic. The collision of these air masses, which have different densities, as well as speeds and directions of motion, forces them to want to switch places very rapidly. This creates updrafts of warm and wet air, which produce thunderstorms. And, as the updrafts climb through the atmosphere, they encounter fast- moving jet stream winds, which change speed and direction with altitude. These changes give the updraft a strong twisting motion that spawns tornadoes.

The severity of tornadoes is rated on the Fujita Scale, which examines how much damage is left after a tornado has passed: F0-F1 tornadoes produce minor damage and so are considered weak, F2-F3 tornadoes produce significant damage and are considered strong, and F4-F5 tornadoes produce severe damage and are considered violent. The problem with this ranking is that it is related to a human-based assessment of damage; you need something (buildings, vegetation, etc.) to be destroyed and someone to see the damage. So, a severe tornado that occurs somewhere where there is nothing to be destroyed would be classed as weak, and one that occurs where there is no-one to see the damage wouldn’t even be counted.

National Oceanic and Atmospheric Administration's VORTEX-99 team observed several tornadoes on May 3, 1999, in central Oklahoma. The tube-like funnel is attached at the top to a rotating cloud base and surrounded by a translucent dust cloud near the ground. Image credit: NOAA.

Still, tornado awareness and volunteer reporting programs, along with good record-keeping, have significantly improved our understanding of tornadoes and their frequency. Surprisingly, the Storm Prediction Center’s tornado database, which goes back to 1950, does not show an increasing trend in recent tornadoes. This finding is confirmed by Dr. Stanley Changnon from the University of Illinois at Urbana-Champaign, whose study of insurance industry records was published last year. Dr. Changnon’s work shows that tornado catastrophes and their losses peaked in the years between 1966 and 1973, but have shown no upward trend since that time. In fact, the number of the most damaging storms, those rated as F2 to F5 has actually decreased over the past 5 decades. So, it does not appear that global warming is increasing the number of tornadoes that occur.

This is actually not as surprising as it seems. While a local increase in temperature and humidity, whether caused by global warming or not, would be expected to create more thunderstorms, it is not clear that these thunderstorms would spawn tornadoes. The reason is that global warming does not increase temperatures the same everywhere. Warming at the poles is expected to exceed warming at more southern latitudes. This means that cold polar air will be much less colder than before and warm Gulf of Mexico air will only be slightly warmer. When these two air masses meet above the southern US, the temperature difference between them will not be so great and their drive to swap places will be much less intense. The result will be a significantly slower moving updraft of warm air that is not expected to produce as many extreme thunderstorms or spawn as many tornadoes.

So, global warming is not expected to increase the total frequency of tornado activity. However, warming global temperatures will mean an earlier spring and the potential for earlier tornadoes. In fact, the early tornado numbers we’ve seen so far this year may be a sign of a global warming-induced shift in the tornado season, according to Dr. Masters. If this is the case, the tornado season may start earlier, but it will also end earlier. As meteorologist Harold Brooks from the National Severe Storms Laboratory in Norman, Oklahoma, points out, this record start to the 2012 tornado season does not necessarily mean the rest of the season will be severe.

Sources:
Recap of deadly U.S. tornado outbreak February 28-March 3, 2012, M. Daniel, EarthSky Mar 5, 2012.
NASA Earth Observatory, March 5, 2012.
Temporal distribution of weather catastrophes in the USA, S.A. Changnon, Climatic Change 106 (2), 129-140, 2011, doi: 10.1007/s10584-010-9927-1.
Does Global Warming Influence Tornado Activity? Diffenbaugh et al., EOS 89 (53), 553-554, 2008.

Joplin, Missouri Tornado Seen From Space

This video from NOAA’s GOES geostationary satellite shows the development of the supercell storm that produced the devastating tornado that struck Joplin, Missouri. Here you can see the storm develop over Missouri, Oklahoma, Kansas state lines on May 22, 2011 between 12:44pm to 7:15pm CDT. This was part of the great wave of severe storms that swept across the central United States, with tornado warnings from Minneapolis to Dallas. The most damaging storm struck Joplin at 5:30 pm local time (2230 UTC), killing at least 116 people.

Below is imagery from the Tropical Rainfall Measuring Mission satellite (TRMM).
Continue reading “Joplin, Missouri Tornado Seen From Space”

F6 Tornado

F6 Tornado

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Everyone knows that tornadoes are among nature’s most powerful and destructive phenomenon on land. Also just like other types of storms tornadoes are ranked by strength. The way that tornadoes are ranked is using the Fujita scale. The Fujita scale is a scale that measures the strength of a tornado by the speed of the winds and the amount of the destruction that it causes. The scale is not perfect in that it is hard to directly measure the speeds of the winds and when looking at damage the guidelines are very general and damage becomes indistinguishable after F3.

The Fujita scale is no longer in use since scientists agreed decommission it in favor of the Enhanced Fujita scale, a more nuanced version of the scale that better ranks tornadoes with detailed guidelines concerning wind and destruction patterns. The Fujita scale is still useful to the average person in giving them a general idea of the strength of a tornado. The interesting thing to look for in the Fujita scale is when it reaches F6 tornado. The F6 is a mythical tornado that you would likely only see in movies or hear of in tall tales. It is similar to the magnitude 10 tornado. Early history may have witnessed such phenomena but they have not occurred in modern times due to more settled climates.

The F6 tornado would be the granddaddy of all tornadoes. It would have wind speeds exceeding 300 miles per hour at maximum and would be able to lift houses from their foundations like Dorothy’s Kansas home in the Wizard of Oz. Car would become ballistic missiles able to hurl at tremendous speeds. However; even if such a tornado existed, it would be hard to identify even with an Enhanced Fujita scale. The damage would look mostly the same as an F5 tornado’s damage. It is thought that the more severe damage would be evidenced by specific funnel marks.

We have written many articles about the tornado for Universe Today. Here’s an article about how tornadoes are formed, and here are some pictures of tornado.

If you’d like more info on F6 tornadoes, check out amazing articles from:
Stormtrack.org
Tornado Project

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Where are Tornadoes likely to Occur

Tornado at Union City, Oklahoma Credit, NOAA Photo Library

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Everyone knows about tornadoes. You may have seen them in movies or heard about them in the news. However one of the most important facts for a person to know is where Tornadoes are likely to occur. This makes simple sense. If you want to avoid hurricanes you know that you should likely not live in the Gulf Coast or Florida. If you want to avoid the chance of mudslides you wouldn’t live in Oregon. Knowing where and how tornadoes can appear can help you stay safer and better prepared in case such a storm happens.

For the most part we know that Tornadoes as they are known in the United States are largely a North American phenomenon. The unique position and composition of North America’s topography gives thunderstorms enough space, time, and energy to form tornadoes. The traditional red zone for tornadoes is the Great Plains region of the United States called Tornado Alley. This region is known for spawning several tornadoes a year and in this region tracking storms and preparing for tornadoes is a way of life. The flat grasslands are perfect place for pressure systems to collide, creating powerful storms and in turn powerful tornadoes.

Interesting enough Tornado Alley is not the only area where tornadoes can happen. Tornadoes can occur anywhere in continental United States if the conditions for tornado formation are met. That means if you have a particularly strong thunderstorm system in your area with high winds there is a strong possibility of a Tornado happening.

The frequency of tornadoes happening outside the Tornado alley have increased with powerful storms ripping up areas that would be by conventional wisdom considered safe such as the Southeast or the Atlantic Seaboard.

One type of location that is generally safe from Tornadoes is the city. However recent events have proven that not likely doesn’t mean never. Two years ago a powerful tornado ripped through downtown Atlanta and doing major damage to the CNN headquarters. The other major tornado in a major city happened recently in New York City. A twister touched down in the Bronx in September of this year in the early morning hours also did serious property damage.

The danger of tornadoes in unlikely locations is that they are harder to spot. The tornado that struck Piedmont, Alabama became one of the deadliest on record because the area was hilly and full of trees. This made it impossible for residents to see the storm funnel approaching. This is why it is important for local news to have good weather tracking systems to properly warn residents in case of unusual weather conditions.

We have written many articles about tornadoes for Universe Today. Here’s an article about the Tornado Alley, and here’s an article about how tornadoes are formed.

If you’d like more info on tornadoes, check out the National Oceanic & Atmospheric Administration (NOAA) Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

What Are Tornadoes?

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.

If you’d like more info on tornadoes, check out the National Oceanic & Atmospheric Administration (NOAA) Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.