By KSN Chief Meteorologist Dave Freeman

Undaunted by the controversy caused by taking on the English system of measurement in my last column, I am ready to open another can of soup! I am going to indulge in pure favoritism when it comes to weather. At the risk of offending others who may scoff at my taste in weather phenomena, I am going to bare my soul and put my choices on the line! I wonder if you have ever been struck by the wonder and beauty of Dave's Fav's:

Crepuscular Rays

Ever been awed by golden columns of light descending from around a cloud? Ever been dazzled by a display of rays seeming to burst from a cloud and rocket skyward? This marvelous phenomenon is known as "crepuscular rays." They are caused by a combination of several factors. First, the sun must be partially blocked by something--usually clouds. Second, there must be some particles in the air to scatter, or reflect, the light of the sun. This can be dust, dirt, smoke, or even water droplets. Those areas with no direct sun appear dark, while those areas receiving direct light of the sun are brightly illuminated. The last part of the recipe is perspective, which allows us to see the rays expanding from their point of origin. This is just like when you stand on a highway and look down the road. As it goes off into the distance it appears to narrow. Of course we know this isn't the case--the highway remains the same width. This concept of perspective is what gives the crepuscular rays the appearance of spreading apart as they come closer to you. I love crepuscular rays and the sense of awe and majesty they can inspire! There is an excellent explanation of Crepuscular Rays on the web.

Hoarfrost

Every time I talk about this one on the air, I get teased about the name. So, let's review that spelling again: Hoarfrost. It is the incredible furry coating of frost that makes the landscape appear as though snow has fallen but that's not the case! In fact, this fascinating weather effect occurs when there is no precipitation at all--no snow, no rain--nothing falling from the sky. Instead, moisture that is contained in the air as water vapor goes directly from water vapor to solid ice crystals. This process is called sublimation. Notice that there is no liquid state here. Temperatures are below freezing and the water vapor doesn't condense into droplets but rather goes directly to forming ice crystals on objects like tree branches, leaves, pine needles, wires, etc. There are occasions when the ice crystals develop to a furry coating that is more than a quarter of an inch (OK .64cm...see last column) thick! It is like you have been put into a Currier & Ives postcard or a magical forest. The best conditions for hoarfrost are clear, calm and cold nights with plenty of moisture in the low levels of the atmosphere. This allows the crystals to deposit over and over again to make the coating thicker and thicker.

A Kansas Sunset

OK, you say, what makes this so special? With all due respect to other places that claim great sunsets, I have to say that Kansas gets my vote for most spectacular, most often. The reason is that little line of hills just off to the West of Kansas known as the Rocky Mountains. The Rockies kindly stick up high enough to cause ripples and eddies in a river of fast moving air in the mid-levels of the atmosphere known as the jetstream. When these fast moving winds blow over the Rockies, and are disturbed by the mountain tops, changes in air pressure and temperature cause clouds to form. These clouds, because they are so high in the atmosphere, are made up of ice crystals. When the setting sun hits those beautiful wisps of cirrus coming over the Rockies, Kansas gets a marvelous treat. And I really do think we get these incredible colors more often and more reliably than anywhere else!

OK, there you go, my highly prejudiced view of most incredible weather phenomena. If you have a different favorite, drop me a line!

Dave Freeman
KSN Chief Meteorologist
weatherlab@ksn.com