Codorus Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Codorus Creek Observatory clear sky chart from 2005-11-06 to 2024-07-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	15% 7% 2 6% 5% 4 5% 4 6% 7% 39%	89820
	Night	15% 7% 3 6% 4 4 4 4 5% 7% 41%	89639
Transparency	Day	42% 7% 12% 23% 14% 2	89580
	Night	41% 7% 12% 23% 15% 2	89483
Seeing	Day	18% 11% 26% 24% 15% 6%	14477
	Night	17% 8% 29% 32% 13% 1	23909

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	15% 7% 3 7% 5% 4 4 3 5% 6% 42%	2517
	11th to 20th	Day	13% 12% 4 11% 5% 4 5% 3 4 5% 33%	2785
	21st to end	Day	16% 12% 4 9% 6% 5% 4 3 5% 5% 32%	3124
February	1st to 10th	Day	14% 10% 2 6% 5% 5% 4 5% 7% 6% 37%	1710
	11th to 20th	Day	14% 9% 2 7% 5% 5% 3 4 5% 5% 39%	1717
	21st to end	Day	18% 10% 3 7% 5% 4 3 3 5% 4 37%	1570
March	1st to 10th	Day	22% 7% 3 6% 4 5% 4 3 5% 7% 36%	3326
	11th to 20th	Day	10% 6% 2 7% 5% 6% 5% 3 6% 7% 43%	3480
	21st to end	Day	20% 8% 3 6% 4 3 3 3 4 5% 41%	3909
April	1st to 10th	Day	14% 9% 3 6% 5% 5% 5% 4 5% 6% 38%	2280
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 5% 7% 43%	2254
	21st to end	Day	17% 7% 2 7% 3 4 4 4 6% 6% 39%	2280
May	1st to 10th	Day	27% 7% 2 6% 4 3 4 4 6% 7% 30%	4034
	11th to 20th	Day	22% 8% 3 7% 5% 5% 5% 4 5% 7% 28%	4393
	21st to end	Day	10% 5% 2 6% 4 4 5% 4 7% 9% 43%	4823
June	1st to 10th	Day	12% 6% 2 6% 4 5% 5% 5% 6% 10% 39%	2660
	11th to 20th	Day	11% 6% 3 6% 5% 5% 5% 5% 7% 9% 40%	2660
	21st to end	Day	9% 4 1 6% 5% 5% 5% 4 8% 9% 44%	2660
July	1st to 10th	Day	8% 5% 2 6% 5% 6% 5% 4 6% 10% 42%	2660
	11th to 20th	Day	6% 5% 2 5% 5% 6% 6% 4 8% 9% 43%	2593
	21st to end	Day	9% 6% 3 7% 6% 5% 6% 5% 8% 9% 36%	2558
August	1st to 10th	Day	8% 5% 3 6% 5% 6% 6% 6% 7% 9% 38%	2327
	11th to 20th	Day	11% 7% 2 7% 5% 4 5% 5% 7% 9% 38%	2211
	21st to end	Day	13% 5% 2 6% 4 4 5% 4 6% 9% 42%	2376
September	1st to 10th	Day	16% 6% 2 5% 4 4 5% 3 4 6% 45%	2160
	11th to 20th	Day	13% 6% 2 5% 3 3 4 3 5% 8% 48%	2160
	21st to end	Day	17% 8% 3 6% 4 3 4 4 4 8% 40%	1905
October	1st to 10th	Day	17% 5% 2 5% 4 4 4 4 5% 7% 43%	1800
	11th to 20th	Day	16% 8% 2 5% 3 3 4 3 5% 6% 45%	1800
	21st to end	Day	16% 7% 2 5% 4 3 4 3 6% 5% 44%	1980
November	1st to 10th	Day	12% 6% 2 4 3 4 3 3 5% 7% 50%	1709
	11th to 20th	Day	15% 6% 2 6% 4 3 4 3 5% 6% 46%	1677
	21st to end	Day	15% 6% 2 5% 5% 4 5% 4 4 7% 43%	1520
December	1st to 10th	Day	17% 7% 3 7% 5% 4 5% 3 7% 8% 34%	1520
	11th to 20th	Day	16% 9% 3 8% 4 5% 4 3 5% 7% 36%	1910
	21st to end	Day	16% 9% 3 8% 5% 4 5% 4 6% 7% 32%	2772
January	1st to 10th	Night	13% 10% 4 8% 5% 5% 4 3 5% 6% 36%	4429
	11th to 20th	Night	17% 9% 3 7% 4 4 4 3 5% 6% 39%	4170
	21st to end	Night	19% 11% 3 7% 5% 4 3 3 4 5% 34%	4532
February	1st to 10th	Night	16% 9% 2 6% 5% 4 4 3 5% 6% 39%	2470
	11th to 20th	Night	16% 9% 3 7% 3 4 4 3 5% 6% 39%	2347
	21st to end	Night	16% 9% 3 7% 4 3 4 4 5% 6% 38%	1884
March	1st to 10th	Night	20% 9% 2 6% 4 4 3 3 5% 5% 37%	3524
	11th to 20th	Night	11% 6% 3 6% 5% 4 4 3 5% 6% 47%	3480
	21st to end	Night	13% 9% 3 7% 4 3 3 3 4 5% 45%	3722
April	1st to 10th	Night	15% 9% 3 7% 4 4 4 4 6% 7% 36%	1900
	11th to 20th	Night	13% 6% 2 6% 5% 4 4 3 6% 8% 43%	1875
	21st to end	Night	17% 6% 3 5% 3 3 4 4 7% 7% 41%	1900
May	1st to 10th	Night	24% 8% 3 7% 4 4 4 3 4 7% 31%	2890
	11th to 20th	Night	22% 8% 2 7% 6% 4 4 4 6% 6% 29%	2495
	21st to end	Night	10% 6% 2 6% 5% 4 5% 4 7% 10% 40%	2732
June	1st to 10th	Night	13% 5% 2 5% 4 4 4 4 6% 7% 46%	1520
	11th to 20th	Night	9% 6% 2 6% 5% 4 5% 6% 6% 11% 40%	1520
	21st to end	Night	8% 5% 2 6% 5% 4 5% 4 8% 10% 43%	1520
July	1st to 10th	Night	7% 7% 3 7% 6% 5% 6% 6% 7% 8% 38%	1520
	11th to 20th	Night	5% 3 2 5% 4 5% 4 6% 8% 10% 48%	1488
	21st to end	Night	8% 5% 2 5% 5% 4 5% 5% 7% 9% 46%	1756
August	1st to 10th	Night	9% 5% 1 5% 4 6% 5% 5% 9% 8% 43%	1611
	11th to 20th	Night	9% 6% 3 8% 5% 5% 5% 4 6% 7% 41%	1669
	21st to end	Night	12% 5% 2 5% 4 4 5% 4 6% 8% 44%	1980
September	1st to 10th	Night	13% 5% 2 7% 4 4 4 3 6% 7% 45%	1800
	11th to 20th	Night	11% 6% 2 4 3 4 4 3 4 7% 53%	1800
	21st to end	Night	17% 6% 2 6% 4 4 4 4 5% 7% 42%	2051
October	1st to 10th	Night	19% 6% 2 5% 4 3 3 3 5% 5% 45%	2160
	11th to 20th	Night	14% 5% 2 5% 4 3 4 3 5% 6% 47%	2160
	21st to end	Night	17% 6% 2 5% 3 3 3 3 5% 7% 46%	2376
November	1st to 10th	Night	11% 6% 2 5% 4 3 3 3 5% 6% 52%	2367
	11th to 20th	Night	14% 7% 3 6% 4 4 4 3 5% 6% 46%	2502
	21st to end	Night	13% 5% 2 6% 5% 4 4 4 6% 6% 44%	2660
December	1st to 10th	Night	16% 8% 3 7% 5% 4 5% 4 5% 6% 37%	2660
	11th to 20th	Night	16% 7% 2 7% 5% 5% 4 4 6% 6% 39%	3285
	21st to end	Night	16% 9% 3 8% 5% 5% 5% 5% 6% 8% 31%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 7% 13% 25% 11% 4	2518
	11th to 20th	Day	50% 7% 10% 17% 12% 3	2785
	21st to end	Day	52% 6% 10% 23% 7% 2	3124
February	1st to 10th	Day	46% 6% 12% 23% 11% 2	1710
	11th to 20th	Day	45% 6% 10% 25% 13% 3	1726
	21st to end	Day	49% 5% 10% 20% 12% 4	1570
March	1st to 10th	Day	47% 6% 10% 24% 11% 2	3326
	11th to 20th	Day	35% 7% 11% 26% 16% 4	3480
	21st to end	Day	45% 5% 9% 22% 16% 3	3909
April	1st to 10th	Day	44% 7% 11% 19% 16% 4	2280
	11th to 20th	Day	40% 6% 11% 22% 17% 4	2254
	21st to end	Day	43% 6% 10% 22% 17% 3	2280
May	1st to 10th	Day	52% 7% 9% 20% 10% 1	4071
	11th to 20th	Day	52% 9% 12% 17% 8% 1	4397
	21st to end	Day	33% 9% 14% 25% 17% 2	4837
June	1st to 10th	Day	38% 8% 13% 24% 16% 1	2660
	11th to 20th	Day	39% 9% 14% 23% 13% 2	2660
	21st to end	Day	33% 8% 14% 27% 16% 1	2660
July	1st to 10th	Day	36% 9% 14% 21% 16% 3	2590
	11th to 20th	Day	33% 8% 15% 26% 15% 3	2518
	21st to end	Day	39% 10% 12% 20% 15% 2	2415
August	1st to 10th	Day	38% 11% 14% 23% 14%	2314
	11th to 20th	Day	39% 8% 13% 22% 15% 2	2211
	21st to end	Day	38% 8% 13% 24% 15% 4	2376
September	1st to 10th	Day	41% 6% 12% 19% 18% 4	2160
	11th to 20th	Day	33% 6% 10% 27% 20% 4	2160
	21st to end	Day	44% 5% 9% 19% 21% 2	1905
October	1st to 10th	Day	40% 6% 11% 24% 17% 2	1800
	11th to 20th	Day	39% 5% 12% 23% 19% 2	1800
	21st to end	Day	41% 6% 9% 25% 18% 2	1980
November	1st to 10th	Day	34% 4 13% 25% 20% 4	1709
	11th to 20th	Day	38% 5% 11% 23% 19% 3	1677
	21st to end	Day	40% 6% 11% 30% 10% 2	1520
December	1st to 10th	Day	47% 5% 15% 21% 10% 1	1520
	11th to 20th	Day	45% 8% 11% 28% 8% 1	1906
	21st to end	Day	48% 9% 15% 18% 9% 1	2772
January	1st to 10th	Night	43% 7% 11% 25% 11% 3	4429
	11th to 20th	Night	43% 6% 12% 25% 12% 2	4170
	21st to end	Night	49% 6% 8% 26% 9% 2	4532
February	1st to 10th	Night	45% 5% 13% 24% 12% 1	2470
	11th to 20th	Night	45% 3 10% 21% 18% 3	2349
	21st to end	Night	45% 6% 10% 19% 14% 5%	1884
March	1st to 10th	Night	47% 6% 10% 25% 11% 1	3524
	11th to 20th	Night	34% 8% 10% 32% 14% 2	3480
	21st to end	Night	41% 5% 7% 21% 21% 4	3722
April	1st to 10th	Night	45% 6% 10% 19% 16% 4	1900
	11th to 20th	Night	38% 7% 11% 21% 19% 5%	1875
	21st to end	Night	40% 6% 10% 22% 17% 4	1900
May	1st to 10th	Night	52% 7% 8% 18% 12% 3	2918
	11th to 20th	Night	52% 10% 11% 14% 11% 1	2496
	21st to end	Night	35% 10% 15% 25% 11% 3	2739
June	1st to 10th	Night	35% 8% 11% 26% 18% 2	1520
	11th to 20th	Night	35% 10% 14% 22% 16% 2	1520
	21st to end	Night	34% 8% 14% 25% 17% 2	1520
July	1st to 10th	Night	39% 11% 14% 19% 13% 3	1480
	11th to 20th	Night	29% 10% 16% 26% 17% 3	1440
	21st to end	Night	31% 10% 17% 22% 17% 3	1658
August	1st to 10th	Night	34% 9% 18% 25% 13% 1	1600
	11th to 20th	Night	40% 9% 13% 20% 17% 1	1669
	21st to end	Night	36% 8% 14% 22% 17% 3	1980
September	1st to 10th	Night	37% 7% 12% 21% 20% 4	1800
	11th to 20th	Night	32% 6% 10% 25% 25% 3	1800
	21st to end	Night	41% 6% 10% 20% 20% 3	2051
October	1st to 10th	Night	40% 6% 13% 23% 16% 2	2160
	11th to 20th	Night	37% 5% 11% 28% 18% 2	2160
	21st to end	Night	37% 5% 10% 27% 18% 2	2376
November	1st to 10th	Night	33% 5% 10% 26% 21% 5%	2367
	11th to 20th	Night	39% 4 9% 24% 19% 5%	2502
	21st to end	Night	37% 5% 12% 27% 16% 2	2660
December	1st to 10th	Night	47% 5% 12% 23% 12% 1	2660
	11th to 20th	Night	43% 5% 13% 22% 15% 2	3288
	21st to end	Night	47% 9% 15% 21% 8% 1	4884

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 20% 34% 16% 5% 1	180
	11th to 20th	Day	26% 23% 32% 15% 4	256
	21st to end	Day	22% 22% 37% 14% 5% 1	297
February	1st to 10th	Day	22% 19% 39% 16% 3 1	270
	11th to 20th	Day	26% 22% 40% 11% 1	324
	21st to end	Day	28% 18% 34% 17% 3	382
March	1st to 10th	Day	19% 19% 32% 25% 5%	460
	11th to 20th	Day	21% 20% 35% 19% 3 2	460
	21st to end	Day	25% 16% 30% 20% 7% 2	506
April	1st to 10th	Day	21% 17% 35% 18% 8% 2	460
	11th to 20th	Day	17% 17% 29% 19% 12% 5%	452
	21st to end	Day	25% 12% 27% 24% 9% 3	460
May	1st to 10th	Day	28% 11% 26% 20% 12% 4	463
	11th to 20th	Day	21% 9% 27% 25% 14% 5%	487
	21st to end	Day	16% 5% 19% 28% 24% 9%	529
June	1st to 10th	Day	15% 7% 26% 26% 18% 9%	490
	11th to 20th	Day	13% 7% 22% 28% 21% 8%	490
	21st to end	Day	11% 5% 24% 31% 21% 8%	490
July	1st to 10th	Day	11% 5% 16% 29% 26% 14%	485
	11th to 20th	Day	5% 3 16% 30% 32% 14%	465
	21st to end	Day	12% 3 18% 32% 25% 9%	488
August	1st to 10th	Day	11% 2 15% 31% 30% 11%	446
	11th to 20th	Day	12% 6% 13% 28% 27% 14%	439
	21st to end	Day	11% 5% 14% 29% 26% 15%	495
September	1st to 10th	Day	18% 5% 16% 22% 22% 17%	450
	11th to 20th	Day	13% 4 15% 30% 23% 15%	450
	21st to end	Day	22% 8% 22% 26% 15% 6%	450
October	1st to 10th	Day	20% 7% 21% 24% 18% 10%	450
	11th to 20th	Day	17% 9% 29% 24% 18% 3	450
	21st to end	Day	17% 10% 36% 25% 9% 3	495
November	1st to 10th	Day	16% 11% 27% 29% 14% 3	383
	11th to 20th	Day	18% 15% 30% 24% 11% 1	337
	21st to end	Day	18% 18% 35% 20% 9%	180
December	1st to 10th	Day	23% 18% 32% 17% 7% 3	180
	11th to 20th	Day	24% 16% 33% 18% 7% 1	180
	21st to end	Day	21% 14% 33% 23% 9% 1	198
January	1st to 10th	Night	17% 13% 43% 23% 3	760
	11th to 20th	Night	21% 14% 32% 29% 4	760
	21st to end	Night	17% 13% 43% 25% 2	836
February	1st to 10th	Night	21% 14% 34% 29% 3	760
	11th to 20th	Night	22% 15% 41% 21% 1	743
	21st to end	Night	21% 16% 41% 19% 3	628
March	1st to 10th	Night	17% 13% 40% 25% 5%	760
	11th to 20th	Night	21% 13% 36% 25% 5%	760
	21st to end	Night	21% 10% 38% 25% 5% 1	836
April	1st to 10th	Night	21% 13% 38% 24% 5%	760
	11th to 20th	Night	17% 9% 34% 31% 9%	751
	21st to end	Night	20% 9% 32% 29% 9%	760
May	1st to 10th	Night	19% 9% 26% 33% 12%	622
	11th to 20th	Night	20% 4 27% 38% 11%	374
	21st to end	Night	14% 3 18% 43% 20% 2	411
June	1st to 10th	Night	13% 2 22% 41% 20% 1	380
	11th to 20th	Night	11% 3 23% 44% 18% 1	380
	21st to end	Night	9% 2 21% 52% 16%	380
July	1st to 10th	Night	8% 3 17% 41% 28% 3	370
	11th to 20th	Night	5% 2 11% 46% 32% 3	360
	21st to end	Night	10% 2 13% 45% 28% 2	576
August	1st to 10th	Night	10% 2 9% 49% 28% 2	537
	11th to 20th	Night	11% 4 10% 40% 31% 3	605
	21st to end	Night	12% 2 13% 37% 32% 4	792
September	1st to 10th	Night	15% 3 16% 34% 29% 3	720
	11th to 20th	Night	12% 2 14% 38% 30% 4	720
	21st to end	Night	20% 3 20% 34% 22% 2	720
October	1st to 10th	Night	22% 4 21% 29% 21% 4	720
	11th to 20th	Night	17% 7% 29% 34% 13% 1	720
	21st to end	Night	20% 5% 36% 28% 10% 1	792
November	1st to 10th	Night	14% 6% 32% 36% 11% 1	740
	11th to 20th	Night	16% 11% 34% 30% 8% 1	760
	21st to end	Night	14% 11% 36% 30% 8%	760
December	1st to 10th	Night	21% 11% 37% 24% 6%	760
	11th to 20th	Night	18% 8% 40% 30% 5%	760
	21st to end	Night	19% 10% 36% 33% 2	836

Page generated at 2024-07-13 10:19:51. Version ac07

Copyright © 2024 Attilla Danko.