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Friday, January 18, 2019

Check out the Lunar Eclipse on Sunday, January 20th.

The eclipse will start at 7:36 pm MST, and will about 5 hours from start to finish. Hopefully it will be clear where you live! To find out more about the timing, etc., here are a couple resources . . .

1. Go to timeanddate.com and enter your location.

2. Read how to watch at theverge.com.

The video below is not specific to the eclipse of January 2019, but it does an nice job of explaining different aspects of lunar eclipses.

Wednesday, January 16, 2019

Enter your address to see where you would have been millions of years ago.

This is a fantastic interactive visualization that was created (and is maintained) by Ian Webster. Once the site opens, enter your address in the box in the upper left, then select the time (in Earth's history) near the top of the web page. To see more of Ian's work, go to ianww.com.

Thanks to Rick Dees for showing me this!

Thursday, December 13, 2018

Classic Chinook Arch over Helena, Montana

A Mountain Wave.
This photo was taken from the Helena High athletic fields, looking west toward the Continental Divide. It shows the classic Chinook arch that appeared on December 13, 2018. The clear area between the arch and the mountains exists because the air is down-sloping there. As air flows over the Rockies it may develop an up and down motion like water flowing over rocks in the rapids of a river. Although the air flows downward once it gets over the mountains, it may continue to oscillate up and down as it flows away from the mountains for several hundred miles. The upward flowing part of this "mountain wave" is what forms the long arch of clouds. (Click on the image to enlarge it or CLICK HERE to watch a 24-second video of the arch shown in the photo.)

Here's how it works.
As the air flows down-slope, it is warmed by compression. Then, as the wave action continues and the air begins to rise again, the air cools by expansion. If there is enough vapor in the air, the arch of clouds will form as vapor condenses to form cloud droplets (or cloud crystals). Typically, the long area of clouds will form near the crest (top) of the first wave and then get blown eastward by higher level winds. If the mountain wave continues, and another downward turn is taken, the arch (cloud) will evaporate farther downstream (east).

Same arch, different vantage point.
The G.O.E.S. East satellite image below shows what the same Chinook arch looked like from space at 9:47 am MST. It is called an "arch" because an observer standing below it sees a curved patch of clear sky between the band of clouds and the mountains below. In the satellite image, the Chinook arch is the distinct eastern edge of the bright white cloud that extends from north to south through western Montana.

Confused? - Check out this Great Falls Tribune article.

Wednesday, December 5, 2018

Make a cloud with your mouth!

This is the coolest activity I've seen in awhile - Lots of good science, and explained very well. Check it out.

Wednesday, November 7, 2018

Mazama Ash in Montana

This photo was taken 12 miles northeast of Helena, Montana. The white streak is a layer of ash from the explosive eruption of Mt. Mazama (Oregon) 7,700 years ago. Geologists can determine where the ash originated by comparing its chemical composition with the compositions of volcanoes found in the region. .

The volume of ash produced by Mazama was forty-two times greater than the amount produced by St. Helens in 1980. Prevailing winds caused the ash to spread eastward. Initially the ash covered much of the ground in the Northwest. But in the months following the eruption, wind and runoff transported the ash to low places (lakes, valleys), where it was eventually buried beneath layers of sediment. Today it can be seen in places where it has been exposed in road-cuts, cut banks, archeological digs, etc. The sediment above the ash layer in the photo to the right was deposited in the centuries after the ash settled here, then the exposed when road construction cut into the slope.

The Mazama ash layer has been found at many other places in the Northwest as well. In fact, Mazama ash serves as a good "key bed" for the region. Key beds help determine relative age - For example, several years ago archeologists came upon Mazama ash while excavating a Paleo-Indian campsite near Helmville, Montana. Mazama ash was exposed at the dig site ABOVE the evidence, indicating that the Indians used the site before the big eruption (at least 7,700 years ago).

The Mazama eruption also emptied significant amounts of magma from the chamber beneath the volcano. As a result, after the eruption the remaining cone collapsed into the chamber, forming a huge crater known as a "caldera". Today, Crater Lake (Oregon) fills the caldera.

For much more about Mazama Ash, CLICK HERE

Also, check out my Montana hiking blog at www.bigskywalker.com - Lots of geology!

Tuesday, October 23, 2018

Understanding Natural Climate Cycles

The connection between Milankovitch Cycles and Ice Ages was established decades ago. However, climatologists have long wondered how such small changes in Earth's tilt and orbit could cause such big changes in climate. This video looks at a possible explanation.

Saturday, October 13, 2018

Check out this Slick Crossword Puzzle-Maker

I wanted to make a crossword puzzle to help my students review some terms that were included in our recent hydrology unit. I found this site: crosswordhobbyest.com - Although the puzzle did not include all of the terms that I entered*, I'm satisfied with the end product. To access the puzzle CLICK HERE, or (to see a different look) click on the "start puzzling" link below.

*Unfortunately the puzzle-maker was not able to include these words: watershed, septic system, recharge, aeration.