Tuesday, December 18, 2007

Rare Diamond Dust Snowflakes Spotted in Lafayette's Snowiest Year on Record

Sun pillar lights up Lafayette last year
Last night we got lucky and missed out on the worst of the freezing fog as Illinois had all of the advisories. We did however have another rare phenomenon that takes place only a couple times a year in Lafayette. We had diamond dust. It is the name of a shimmering and sparkling snowflake that kind of just floats in the sky. Temperatures have to be well below freezing and its more common in the far northern latitudes. Fairbanks, Alaska has plenty of diamond dust reports. Believe it or not, this special type of snow can actually take place when there aren't any clouds.

Sure enough last night the moon was out in West Lafayette and the stars were shining brightly when I saw these floating ice crystals in my car headlights. Basically they are floating ice crystals that form in freezing fog. The very cold air in the teens and lower 20s last night was saturated in high humidity. This allowed the high water vapor content in the air to condense out into ice crystals. This process is more prevalent at 25,000 feet in the sky, not at ground level. Wispy cirrus clouds you can say have plenty of diamond dust in them. Diamond-dust crystals are six-sided ice crystals just like other types of snow but are made of small irregular hexagonal plates instead of larger star-like flakes. This is what makes them sparkle like gemstones.

Some folks in the Arctic have told stories about being able to walk through a diamond dust cloud and then turn around and see a tunnel matching perfectly the outline of their body, where the sparkling ice crystals have disappeared, almost like footprints in the snow. This can happen because your body is literally pushing away the suspended ice crystals in the fog. These ice crystals have also been known to create sun pillars, moon pillars, and light pillars that look like beams from the horizon straight into the sky. Here in Lafayette we had a dramatic display you may have remembered in the picture above. The plate-like ice crystals become like mirrors as light is reflected above and below them with extraordinary results.

It is fitting we had this take place last night in the year of the snow. I have gone through most of the last 100 years of snowfall in Lafayette and this year we have had more snow than any other thanks to the blizzard and huge December snowstorm. It may not have been our snowiest season on record but just taking the year 2007 as a whole, it is number one on the list of snowiest years. Here is an impressive chart.

Even the great blizzard year of 1977 is no match for 2007! That is unbelieveable. The third highest snow year I could find was 1982 that was buried with 41.5 inches of snow. Keep in mind on average here in Lafayette we have 22.4 inches of snow every year. So we are long overdue for a pattern change and it does look like the pendulum is about to swing the other way as we finish out the last 13 days of the snowiest year on record. I think we will have a couple cold snaps, but overall it should be milder than average and quiet with no big snowstorms or ice storms in sight. If you want to see a big snowstorm head west as the pattern does a flip-flop. The Pacific flow is about to take over. This is typical of a La Nina pattern that is known for wild swings in temperatures and precipitation. This weekend we have a better chance of a thunderstorm on Saturday than snow. What a change! But remember the pendulum will swing back to snowy and cold just like we saw last February. So snow-lovers congratulations on your new record and may 2008 bring a lot more snow and diamond dust! It always is interesting in Indiana!


Anonymous said...

I am thankful the freezing fog stayed away from us as I had to travel into IL. I had good driving weather both ways!

Mary Anne in Remington

Anonymous said...

No White Christmas??? Bah Humbug!