Sunday, January 27, 2008

Weather and Optical Illusions

Good Sunday to you!

I was thinking back on winters I've spent working in other parts of the country and I thought about how this time of year when I was in Michigan I saw light pillars eminating from atop light poles when I'd drive home on very cold nights.

Since our weather is rather quiet today I thought I'd give you a little quiz about about optical phenomena.

Which one of the following is *not* associated with weather?

a) Solar (light) pillars (okay, that was a giveaway..)

b) Cloudbows

c) frog nimbus

d) sun dogs

The answer is c) frog nimbus. But believe it or not, there is actually a type of frog with nimbus in its name (the things you learn when you Google something!).

The frog's name is Crinia nimbus
Family: Myobatrachidae
It is dark brown on its back with darker patches on the body (above the line of the arms), lower back and sides. A dark stripe runs from the snout, through the eye and broadens behind the eye to enclose the tympanum (tight membrane covering the entrance to the ear). The dark stripe is boarded below by a white stripe. The belly is dark brown with white spots. The throat and arms sometimes have a yellow tinge. Fingers and toes are not fringed.
Size: 25 - 30 mm
This frog lives in cloud forests in the subalpine moorlands and lowland rainforests of Tasmania.

(So thats your "Hey Mable" moment for the weekend. I dare you to try to work *that* into the water cooler talk on Monday!)

About our other weather phenomena....

a) Solar (light) pillars:

Columns of light apparently beaming directly upwards from uncovered lights are sometimes visible during very cold weather. Plate shaped ice crystals, normally only present in high cirrus clouds, float in the air close to the ground and their horizontal facets reflect light back downwards. The pillars are not physically over the lights or anywhere else in space for that matter. They are purely the collected light beams from all the millions of crystals which just happen to be reflecting light towards your eyes or camera.
A Solar Pillar occurs when the sun is reflected so strongly that the reflection is almost as bright as the sun itself. In the daytime the pillar appears to move when the observer moves, but always remains directly below the sun. Like a rainbow, this sight is dependent on where the light is coming from and where the observer is standing.

b) Cloudbows:

A Cloudbow is similar to a rainbow (can also have fogbows), but without any colors due to the very small size of the water droplets.

d) Sun dog:

A sun dog also referred to as mock sun is a colorful patch of light that is caused by the refraction of sunlight by tiny six-sided crystals of ice within the atmosphere. When the sunlight passes through the crystals of ice, it is bent by 22 degrees before reaching the eyes of the observer, thus producing a sun dog. The sun dog scientifically known as parhelion is actually an atmospheric optical phenomenon (the phenomenon involving light). A group of sun dogs are known as parhelia( meaning with the sun).

As far as our quiet weather for the next day or so, we have high pressure moving eastward to NC this second half of the weekend. we'll hvae beautiful blue skies, but it will be a little breezy. this means it will feel colder than our forecasted highs in the upper 40s.
We're looking for clear skies tonight, which means cold temperatures for the morning commute! lows 27-29 with light N winds.
Monday will start out sunny but we'll see clouds move in at night. Highs Monday in the low to mid 50s, lows with cloudy skies in the low to mid 30s.
Mild weather Tuesday with cloudy skies and a chance for rain showers developing - high 63, low 44.
Have a great week!
Pati Darak

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