Tag: photographs

Nashville flooding and mid-latitude cyclones

Nashville, TN, May 4, 2010. (photo by David Fine/FEMA)
Daily weather map for May 2nd, 2010. Note the cold front heading toward Nashville. Map from the Hydrometeorological Prediction Center.

Over 30 cm of rainfall in just two days resulted in extensive flooding in Nashville, TN, last week. The precipitation was produced by one of those typical mid-latitude cyclones that sweep across the United States, from west to east, every spring and fall. The Boston Globe has some amazing picture of the flooding.

The news media tends to have the most dramatic photographs of disasters, but the Federal Emergency Management Agency (FEMA) also tends to have good images from their aerial surveys (like the image at the top of this post). And images produced by the government are in the public domain so you don’t have to worry about using them.

May 2-6 fronts. Animation generated using images from the HPC.

For discussing warm fronts, cold fronts and mid-latitude cyclones, NOAA‘s Hydrometeorological Prediction Center (HPC) is a great resource. You can find an archive of daily weather maps for the U.S. that you can click through to see the fronts move.

Infra-red satellite image of the continental U.S.. Note the alignment of the clouds and precipitation with the fronts in the first (static) weather map above. (Image from GOES).

Satellite imagery usually complements to the frontal weather maps very well. Most satellites orbit around the Earth pretty quickly, at just the right orbital speed that the centrifugal force just balances the Earth’s gravity so the satellite does not crash into the atmosphere or escape into space. Some satellites are set into orbit a bit further out so that they can rotate with the Earth, effectively staying above the same place all the time. NOAA has a few of these geostationary satellites monitoring the weather around the world, and you can get real-time images from the Geostationary Satellite Server. There used to be archived satellite images but I can’t seem to find them at the moment.

Best nature photos

The Guardian newspaper put together an excellent collection nature photographs for auction for an Earth Day charity. I particularly like the pictures from the Franklin River, south-west Tasmania, Australia and Stone Canyon, Arizona/Utah, U.S.A.. Apart from the wonderful composition and spectacular lighting, I like the effort and meaning behind these images.

Slickrock Formation, Paria Canyon (from Thundafunda). As beautiful as it is, this is not the Stone Canyon photo in the list.

According to the Guardian, the Franklin River image was instrumental in preventing the flooding of the river for an hydroelectric dam. The Stone Canyon picture was used to try to have the area declared a national monument. I particularly appreciate the effort of Jack Dykinga, who took the Stone Canyon photo. He hiked up the slot canyon at 3:30 am in order to get the photograph at dawn; with their softer light and reddish tints, sunrise and sunset are the best times for photography.

Integrating Eyjafjallajökull

Second fissure, viewed from the north, on 2 April 2010 (from Wikipedia)

Current events often generate the teachable moments we’re always seeking in order to strike students’ imagination. The eruption of Eyjafjallajökull is a prime example. I’ve already used it to point out the intersection of geothermal energy and plate tectonics, but there is so much more.

The second eruption in Eyjafjallajökull. Seen from Fljótshlíð on 20 April 2010 (from Wikipedia).

Eyjafjallajökull has been a wonderful subject for the art of photography. The image above is a great example but the time-lapse photos have been excellent. The photo to the right captures not just the stars streaking across the sky with a three minute exposure but the fiery red arcs of the volcanic ejecta.

The MODIS instrument on NASA's Aqua satellite captured an ash plume from Eyjafjallajökull Volcano over the North Atlantic at 13:20 UTC on 17 April 2010 (from NASA via Wikipedia).

One of the major benefits of the space program so far has been its Earth observing satellites. There is so much going on in the image to the left that it’s hard to know where to start. Why are there all those clouds over Iceland? (warmer land mass creates convection); what’s with the two plumes from the volcano, one concentrated high level and one disperse low level plume; fjords on the upwind side of the island and the straightened coastline on the lee; greenish plumes of glacier-ground, rock flour discharging into the ocean.

Dust particles suspended in the atmosphere scatter light from the setting sun, generating 'volcanic lavenders' like this one over the flight path of Leeds-Bradford Airport in England during the aviation shutdown. (from Wikipedia).

The dinosaurs were done in either by an asteroid impact in the Yucatan or the eruption of the massive flood volcanoes in Deccan, India, or quite probably both. Both of these events launched an enormous amount of ash, gas and fine particles into the upper atmosphere, blocking sunlight, causing global cooling. Well the ash from Eyjafjallajökull and the sulfur dioxide gas may be having a similar effect on Europe, and if there’s enough of it, on the world. The 1992 eruption of Mt. Pinatubo cooled the globe by about half a degree Celsius.