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Thursday, May 16, 2019

Draw the orbits of the planets on your city.

This is a really cool way to help students understand the size of the solar system. Go to this website, and center the map on your city. This can be done entering your latitude and longitude, or you can expand the map* to full screen and then manipulate it so that your city is at the center. Then enter "33223 mm" for the diameter of the Sun - This is how big the Sun would be if the Earth were the size of a standard globe (12 inches in diameter). Finally, select "calculate" and "show orbits".

*If you expand the map to "full screen" you will need to get out of "full screen" to enter the diameter of the Sun.

Below: To see where the planets are right now, go to this website.

Saturday, March 23, 2019

Losing Ground - a documentary about urban sprawl

Maybe we (Earth Science teachers) should spend more time teaching students about soil (the forgotten natural resouce) and help students understand this issue. We lose 175 acres of land to urban sprawl every hour! The documentary will premiere on May 27,2019 and then will be available on the "Angus TV" YouTube Channel after that - Mark your calendar.

Friday, March 1, 2019

Kelvin-Helmholtz Clouds Caused by Wind Shear

The right place, at the right time.
This photo of an amazing Kelvin-Helmholtz cloud was taken on January 26, 2019 by Hannah Martin, one of my freshman Earth Science students at Helena High School. She snapped the photo from the Helena Valley, looking west - Mount Helena can be seen on the left, and the distant horizon marks the Continental Divide. Also known as "fluctus" or "billow" clouds, they were named after Lord Kelvin (1824-1907) and Hermann Von Helmholtz (1821-1894) who identified the type of instability responsible for the unique waves. Such clouds are fairly rare, and may only last for a few minutes.

Like wind across water.
The waves form at the boundary between layers of air that have different densities and wind speeds (wind shear). Air in the layer above the cloud is moving faster than air in the layer containing the cloud. Development of waves on the cloudy layer is similar to what happens when waves form on the ocean as wind blows across the water. In the photo the wavy layer is more dense than the clear air flowing above it - just as water is more dense than air blowing over its surface.

Clouds provide a "visual".
The type of motion that causes the wave pattern is actually not that uncommon in the atmosphere, although we usually don't see it. In order for us to see it, clouds must be present in the lower layer (as they were when the photo was taken). We can't see clear air, but we can see clouds. One of the nice things about clouds is they provide clues about the type of motion currently happening in the atmosphere. Want to know more? - Watch the 4.5-minute video below, which includes a great demo.

Term for students to define: wind shear

1. Article - More about KH Clouds

2. Another good article about KH Clouds

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.

Term to define: GOES East Satellite

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.