Sunday, August 30, 2015

Conflicting Forecasts

Contradictory Predictions 

Meteorologists often fail to correctly forecast cloud cover. On August 25th one weather forecasting service predicted cloudy skies all day. Another forecasting service predicted completely clear skies and good seeing for a few hours after noon. The forecasts were contradictory! What actually happened?

The sky was almost completely clear around noon, giving me confidence in the reliability of the clear sky forecast. This temporary absence of clouds was the first opportunity in weeks to use my telescope. A few days before August 25th a relatively small sunspot evolved into a giant active complex feature. For days I watched it grow as it moved east to west across the Sun's face. Sunspot activity has been sparse lately, so this unusual episode of clear sky was an opportunity I didn't want to miss. If I didn't catch the sunspot this day, it would rotate out of sight before the next clear day. So I hustled and hauled my equipment outside. It takes about 45 minutes to set up the telescope, acquire the Sun, tune the solar filter, and get the computer and camera ready for imaging. During the setup time I'm usually looking at the equipment and not the sky. Consequently, I was shocked to discover thin clouds drifting across the first images on the computer screen. When I looked around the sky I saw massive cloud banks moving in from the north and west! The clouds had almost covered the sky in the 45 minutes it took to get my equipment ready!

I hurried to capture a few videos through cloud gaps before the situation became hopeless. Fortunately, a few images were relatively unaffected by clouds. The first picture below shows the large sunspot 2403 I had hoped to capture. (Click on the images for a larger view.) Some bright white energetic emissions appear in the space between the giant double umbra on the right and the four smaller trailing umbras on the left. There is good detail in the image, particularly the different shades of darkness in the four trailing umbras. This image was made with a 5X Barlow lens by stacking the 100 best frames from a 1000-frame video.
A few minutes before the previous image was captured the sunspot looked like the next picture made by stacking the best 40 frames from a 400-frame video.
This second image was processed differently than the first image. I think some details are slightly sharper in the second image, and there are subtle differences between the second image and the first.

What a shame the clouds halted my session after less than an hour! The Sun had several nice filaments and prominences in addition to the large sunspot. I started capturing images for a whole disc mosaic, but had to stop after only nine panels were recorded. The next image is a 9-panel imperfect mosaic showing the immediate area around sunspot 2403. The Sun was in and out of clouds during the entire acquisition time.
To the left of center is a region of sharp spicules. On the extreme right center edge you can see the bottom of a huge hanging prominence lifting straight out from the solar limb. Too bad I didn't capture more of this hanging feature. (Click on the image to see these features more clearly.)

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People say I'm crazy doing what I'm doing
Well they give me all kinds of warnings to save me from ruin
When I say that I'm o.k. well they look at me kind of strange
Surely you're not happy now you no longer play the game

People say I'm lazy dreaming my life away
Well they give me all kinds of advice designed to enlighten me
When I tell them that I'm doing fine watching shadows on the wall
Don't you miss the big time boy you're no longer on the ball

I'm just sitting here watching the wheels go round and round
I really love to watch them roll
No longer riding on the merry-go-round
I just had to let it go

John Lennon