Monday, May 06, 2013

Canadian Shoreline Visible? Not So Fast

Over the weekend, Jay Reynolds, local Cleveland Astronomer sent me a photo of an optical illusion over Lake Erie. Its called REFRACTION!

While it looks as if we can actually see the Canadian side of the lake, in reality, its over 50 miles away! Why can we see it in this photo?




The light from the Canadian shoreline is refracted (or bent). The rapid change in air density and temperature between the warm air aloft (70s) and cool air over the lake (40s) acts to bend the light down. The wind needs to be calm for this to happen so that the different air layers don't mix too much.  The result is we see that light here in Ohio when under normal circumstances, that light would have been "beamed" into the atmosphere away from our field of view.

Close up of Optical Refraction (Canadian Shoreline): Courtesy: Jay Reynolds


While it looks like the Canadian shoreline is close, its actually a mirage and over 50 miles away!

Another atmospheric phenomena I witnessed late last week was a ring around the sun at noon Friday. What causes this?


The perpetual cloud cover we've seen are cirrus clouds. These are made of ice crystals and don't produce any precipitation. Many of the ice crystals are hexagonal. If the ice crystals are oriented at just the right position, the sunlight is refracted (there's that word again!).



The sunlight is deflected twice inside the ice crystal.

Courtesy: http://en.wikipedia.org/wiki/File:Path_of_rays_in_a_hexagonal_prism.png

As the light interacts with more ice crystals, it will form a ring of light at exactly 22 degrees from the sun or moon. Some of the light is dispersed broken up into its component colors) as it is refracted inside the ice crystal.


Special thanks to the University of Illinois website for the great graphics!

Wednesday, May 01, 2013

US Temperatures: April 2012 vs April 2013



What a difference a year makes! WELL BELOW NORMAL APRIL ACROSS THE US!

   

What I find interesting is that the center of the "colder than average" area has stayed virtually the same since the beginning of the year.

Here are the April temperatures compared to the average across North America

 Once we include MARCH AND APRIL, the map looks virtually identical

 
How about FEBRUARY, MARCH and APRIL? Little change in the map

The entire year from JANUARY through APRIL shows how the center of the cold evolved over the last 4  months

The BIG QUESTION will be whether or not the CORE OF THE COLDER THAN NORMAL AIR breaks down, drifts west or east or expands?  More on this later.....