Tuesday, December 27, 2011

Dust storm

Every week I get an email with different satellite views that showcase some interesting elements of weather. This week, I received a picture of a serious dust storm that was taking place in Afghanistan on December 20. The dirt is being driven by strong north winds, carrying the dust over the Arabian Sea. Dry lakebeds near the Iran/Afghan border are the most common sources of blowing dirt. Dust storms in Afghanistan can happen any time of the year, but they are more common in the summer months. The average is 6 days a month with dust storms in the summer, but it drops to 2 dust storm days (on average) in the winter season.

Almost everyone reading this has probably been in or around some blowing dirt, but maybe not one where the visibility was almost zero.

Seems like we had our share of blowing dirt this summer with all of the dry weather that we had across the central and southern US. Dry weather is likely to be with us until the 8th or 10th of January. Eventually, by the middle of next month (January), we'll start to enter the active pattern once again with storms coming out of the southwest US. Check back for updates. The mild weather to end 2011 might fool you, but cold air will find us before too much longer.

Tuesday, December 13, 2011

White Christmas 2011?

The chance of a White Christmas is very low for Kansas. In most cases, the chances are only 10-20%, and we define a White Christmas by having at least 1" of snow on the ground from a previous storm, or it could fall on Christmas.

Looking ahead, there are two more storms that should be coming through the central US, and each one of them will be very different. The first one should arrive on Monday, December 19th and this storm will approach from the southwest. This type of storm in the winter can produce a wide variety of weather for Kansas. This one should track to the south of our area, which will put Kansas in a favorable spot to see more moisture. Most of it will be rain, but there is a chance we could see some snow in central and northern Kansas. It is too early to predict accumulations, but even if we do get accumulating snow on Monday, it will likely melt during the middle of the week.

A second storm will move through the area on Friday, December 23, but this one will not likely produce measurable rain or snow for Kansas. The heavier precipitation and snow looks to stay north of our area. However, it will set us up for colder weather going into the Christmas holiday.

So in summary, don't expect a White Christmas this year in Kansas. We'll have to wish for one in 2012.

Tuesday, December 6, 2011

A different view

This is by far one of the most beautiful pictures I've seen of our atmosphere, taken from the International Space Station, which is about 250 miles above us. One of the things I teach to school kids is that the Earth's atmosphere is made up of layers, starting with the troposphere (the lowest layer where we are). Next up is the stratosphere, then mesosphere, and finally, the thermosphere. When you get higher than the thermosphere, you are moving into outer space. The orange-reddish color is the troposphere, which is more dense than the other layers of the atmosphere. The brown color is the tropopause (the division between the troposphere and the stratosphere), and the milky white color would be the stratosphere. The mesosphere and thermosphere fade from shades of blue to black. We are able to see these particular colors because the different gasses act to filter out certain colors that we see with our eyes. The moon may appear to be part of our atmosphere, but it is almost 240,000 miles away, putting it outside of the gaseous envelope that surrounds our planet.

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