Carp Library / Diefenbunker
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carp Library / Diefenbunker clear sky chart from 2005-11-06 to 2024-11-05.

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	16% 9% 3 8% 5% 5% 5% 4 5% 7% 33%	101587
	Night	17% 11% 4 9% 5% 5% 4 4 5% 6% 31%	97461
Transparency	Day	50% 3 12% 23% 10% 1	105083
	Night	53% 3 11% 21% 10% 1	102054
Seeing	Day	23% 13% 30% 21% 10% 3	14472
	Night	23% 10% 28% 28% 10% 1	23551

By Month

Percentage Cloud Cover NE (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% 15% 4 12% 7% 6% 5% 4 5% 5% 22%	2517
	11th to 20th	Day	13% 14% 5% 14% 7% 6% 5% 3 5% 6% 22%	2520
	21st to end	Day	14% 18% 7% 12% 8% 6% 5% 3 4 4 18%	2909
February	1st to 10th	Day	14% 15% 4 11% 7% 6% 4 4 5% 5% 24%	1710
	11th to 20th	Day	12% 14% 5% 10% 6% 5% 4 3 5% 6% 29%	1663
	21st to end	Day	18% 13% 4 9% 5% 4 6% 4 5% 5% 26%	1564
March	1st to 10th	Day	21% 14% 3 9% 6% 5% 4 3 4 4 27%	3140
	11th to 20th	Day	12% 15% 4 10% 6% 6% 5% 4 5% 6% 28%	3480
	21st to end	Day	13% 9% 3 6% 5% 4 4 3 5% 6% 43%	4006
April	1st to 10th	Day	22% 10% 3 6% 5% 4 4 3 4 6% 32%	2280
	11th to 20th	Day	22% 8% 2 7% 5% 4 3 3 4 4 36%	2254
	21st to end	Day	22% 10% 3 7% 5% 3 5% 4 4 5% 32%	2413
May	1st to 10th	Day	20% 8% 3 8% 5% 4 5% 4 6% 6% 32%	4426
	11th to 20th	Day	16% 9% 3 8% 5% 4 5% 4 5% 7% 33%	4398
	21st to end	Day	15% 7% 2 6% 5% 5% 4 4 6% 7% 39%	4837
June	1st to 10th	Day	20% 9% 3 7% 5% 5% 5% 4 5% 7% 30%	2660
	11th to 20th	Day	13% 6% 3 6% 4 4 5% 5% 6% 8% 39%	2660
	21st to end	Day	18% 7% 3 6% 5% 5% 5% 5% 6% 7% 32%	2660
July	1st to 10th	Day	11% 6% 2 7% 6% 5% 6% 5% 7% 10% 35%	4440
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 7% 9% 41%	4440
	21st to end	Day	10% 6% 2 6% 4 4 5% 4 7% 9% 44%	4814
August	1st to 10th	Day	14% 6% 3 8% 5% 5% 6% 4 6% 8% 36%	4330
	11th to 20th	Day	16% 6% 2 7% 4 5% 5% 4 6% 8% 38%	4014
	21st to end	Day	12% 6% 2 6% 4 4 5% 4 7% 10% 40%	4180
September	1st to 10th	Day	12% 6% 3 6% 5% 5% 5% 4 5% 8% 42%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 6% 8% 46%	2280
	21st to end	Day	16% 6% 2 6% 4 5% 5% 4 6% 7% 39%	2022
October	1st to 10th	Day	19% 7% 3 7% 4 5% 5% 3 6% 7% 35%	1900
	11th to 20th	Day	21% 8% 3 7% 5% 5% 5% 3 5% 7% 30%	1900
	21st to end	Day	24% 10% 3 7% 5% 4 5% 3 4 7% 28%	1948
November	1st to 10th	Day	15% 8% 3 7% 6% 6% 5% 4 6% 7% 34%	1704
	11th to 20th	Day	19% 12% 3 8% 5% 5% 5% 4 5% 6% 28%	1520
	21st to end	Day	20% 13% 4 10% 6% 5% 6% 4 5% 5% 20%	1520
December	1st to 10th	Day	20% 19% 4 10% 7% 5% 5% 4 5% 6% 16%	1520
	11th to 20th	Day	21% 14% 4 10% 5% 4 4 4 5% 5% 24%	1906
	21st to end	Day	28% 16% 6% 12% 5% 3 3 2 2 3 19%	2772
January	1st to 10th	Night	16% 17% 6% 14% 6% 4 4 4 4 6% 19%	4429
	11th to 20th	Night	12% 13% 5% 13% 8% 6% 5% 4 5% 5% 23%	4440
	21st to end	Night	17% 20% 7% 10% 6% 6% 4 3 4 4 21%	4744
February	1st to 10th	Night	14% 15% 4 12% 7% 5% 6% 4 5% 6% 23%	2470
	11th to 20th	Night	13% 13% 5% 12% 7% 5% 3 3 5% 5% 29%	2403
	21st to end	Night	16% 12% 4 9% 6% 5% 5% 3 6% 6% 28%	1889
March	1st to 10th	Night	21% 12% 4 9% 5% 4 4 3 3 5% 31%	3697
	11th to 20th	Night	16% 15% 5% 11% 5% 4 4 4 5% 5% 26%	3479
	21st to end	Night	15% 8% 3 7% 4 4 4 3 5% 6% 40%	3626
April	1st to 10th	Night	20% 10% 3 8% 5% 4 4 3 4 6% 33%	1900
	11th to 20th	Night	19% 10% 2 8% 4 4 4 3 5% 6% 35%	1875
	21st to end	Night	20% 9% 3 8% 5% 5% 3 3 4 6% 33%	1780
May	1st to 10th	Night	20% 8% 3 7% 5% 5% 4 5% 7% 7% 30%	2514
	11th to 20th	Night	19% 8% 3 6% 4 5% 4 4 5% 7% 35%	2495
	21st to end	Night	13% 6% 2 7% 4 5% 5% 5% 6% 7% 39%	2738
June	1st to 10th	Night	15% 7% 2 8% 6% 5% 5% 5% 7% 8% 34%	1520
	11th to 20th	Night	14% 6% 2 7% 4 4 4 3 6% 8% 43%	1520
	21st to end	Night	18% 8% 2 5% 5% 4 4 4 6% 7% 37%	1520
July	1st to 10th	Night	11% 7% 3 9% 6% 6% 5% 5% 6% 8% 34%	2520
	11th to 20th	Night	13% 5% 2 6% 5% 4 5% 4 5% 8% 42%	2520
	21st to end	Night	9% 7% 2 6% 5% 5% 5% 4 6% 8% 43%	2739
August	1st to 10th	Night	11% 6% 3 8% 4 5% 5% 4 6% 9% 39%	2596
	11th to 20th	Night	12% 7% 3 7% 4 4 5% 4 6% 8% 41%	2785
	21st to end	Night	12% 6% 3 7% 5% 4 5% 4 6% 8% 41%	3473
September	1st to 10th	Night	11% 5% 2 6% 5% 4 5% 4 5% 6% 47%	1900
	11th to 20th	Night	14% 4 2 5% 3 4 4 3 5% 7% 49%	1900
	21st to end	Night	17% 6% 2 6% 5% 3 3 3 5% 6% 43%	2155
October	1st to 10th	Night	16% 8% 3 6% 5% 4 5% 3 6% 6% 38%	2280
	11th to 20th	Night	20% 9% 4 7% 5% 5% 5% 3 5% 6% 31%	2280
	21st to end	Night	22% 10% 3 7% 4 5% 5% 4 4 6% 28%	2649
November	1st to 10th	Night	19% 11% 3 7% 4 4 3 3 5% 6% 34%	2473
	11th to 20th	Night	19% 11% 4 7% 5% 5% 5% 4 5% 6% 29%	2660
	21st to end	Night	21% 13% 4 9% 5% 5% 5% 3 5% 6% 23%	2660
December	1st to 10th	Night	20% 17% 4 10% 6% 5% 5% 4 5% 5% 17%	2660
	11th to 20th	Night	21% 15% 4 9% 5% 4 4 3 4 4 26%	3288
	21st to end	Night	30% 17% 3 11% 4 4 3 3 3 4 17%	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	66% 1 13% 12% 6% 1	2518
	11th to 20th	Day	66% 2 10% 15% 7% 1	2520
	21st to end	Day	71% 3 10% 11% 5% 1	2909
February	1st to 10th	Day	62% 3 9% 20% 4 2	1710
	11th to 20th	Day	57% 3 11% 18% 10% 1	1672
	21st to end	Day	59% 3 10% 15% 11% 1	1564
March	1st to 10th	Day	62% 2 8% 18% 10% 1	3143
	11th to 20th	Day	59% 2 10% 16% 11% 2	3480
	21st to end	Day	44% 2 6% 25% 20% 3	4006
April	1st to 10th	Day	54% 2 6% 21% 14% 3	2280
	11th to 20th	Day	52% 1 6% 22% 16% 2	2254
	21st to end	Day	56% 2 7% 16% 15% 4	2413
May	1st to 10th	Day	53% 2 7% 24% 11% 2	4440
	11th to 20th	Day	52% 2 12% 22% 10% 1	4402
	21st to end	Day	46% 2 11% 24% 15% 2	4837
June	1st to 10th	Day	53% 3 9% 22% 12% 1	2660
	11th to 20th	Day	42% 4 12% 26% 13% 2	2660
	21st to end	Day	50% 4 13% 22% 11% 1	2660
July	1st to 10th	Day	42% 6% 14% 26% 12% 1	4370
	11th to 20th	Day	37% 6% 14% 33% 10%	4365
	21st to end	Day	36% 5% 14% 34% 12%	4661
August	1st to 10th	Day	45% 4 16% 25% 10%	4316
	11th to 20th	Day	42% 5% 15% 29% 9%	4053
	21st to end	Day	39% 5% 15% 28% 12% 1	4180
September	1st to 10th	Day	40% 3 14% 31% 12%	2280
	11th to 20th	Day	35% 4 13% 33% 13% 1	2280
	21st to end	Day	44% 4 14% 28% 10%	2022
October	1st to 10th	Day	47% 5% 12% 29% 7%	3160
	11th to 20th	Day	46% 5% 14% 26% 9%	3140
	21st to end	Day	49% 5% 18% 21% 7%	3186
November	1st to 10th	Day	49% 3 14% 26% 7% 1	1704
	11th to 20th	Day	58% 4 13% 16% 9% 1	1520
	21st to end	Day	65% 4 12% 11% 7% 1	1520
December	1st to 10th	Day	70% 3 10% 12% 4 1	1520
	11th to 20th	Day	63% 3 13% 15% 6%	1906
	21st to end	Day	73% 2 7% 15% 3	2772
January	1st to 10th	Night	68% 2 14% 12% 4	4429
	11th to 20th	Night	65% 2 13% 15% 5%	4440
	21st to end	Night	69% 2 10% 12% 7%	4744
February	1st to 10th	Night	62% 3 9% 18% 7% 1	2470
	11th to 20th	Night	58% 2 10% 20% 9% 1	2405
	21st to end	Night	57% 2 9% 20% 10% 1	1889
March	1st to 10th	Night	59% 1 8% 20% 10% 2	3707
	11th to 20th	Night	61% 2 11% 16% 8% 1	3480
	21st to end	Night	46% 2 7% 23% 19% 4	3626
April	1st to 10th	Night	54% 2 7% 19% 15% 2	1900
	11th to 20th	Night	51% 3 6% 22% 16% 2	1875
	21st to end	Night	54% 3 7% 17% 16% 3	1780
May	1st to 10th	Night	55% 2 8% 23% 10% 3	2520
	11th to 20th	Night	50% 2 11% 24% 12% 2	2496
	21st to end	Night	44% 2 12% 22% 18% 2	2739
June	1st to 10th	Night	47% 4 12% 25% 10% 1	1520
	11th to 20th	Night	40% 3 11% 26% 18% 2	1520
	21st to end	Night	45% 5% 12% 22% 14% 1	1520
July	1st to 10th	Night	45% 7% 13% 20% 13% 1	2480
	11th to 20th	Night	39% 7% 12% 34% 9%	2472
	21st to end	Night	38% 6% 14% 27% 15%	2651
August	1st to 10th	Night	41% 6% 15% 26% 12% 1	2586
	11th to 20th	Night	40% 5% 17% 30% 8%	2812
	21st to end	Night	39% 6% 14% 26% 12% 2	3473
September	1st to 10th	Night	37% 4 11% 32% 15% 1	1900
	11th to 20th	Night	35% 3 13% 36% 10% 1	1900
	21st to end	Night	42% 3 11% 32% 12%	2155
October	1st to 10th	Night	40% 5% 12% 31% 12%	3800
	11th to 20th	Night	47% 4 15% 25% 9%	3779
	21st to end	Night	49% 5% 17% 20% 8%	4361
November	1st to 10th	Night	51% 3 13% 22% 9% 1	2473
	11th to 20th	Night	56% 3 11% 19% 10% 1	2660
	21st to end	Night	61% 4 13% 16% 6%	2660
December	1st to 10th	Night	69% 3 9% 15% 4	2660
	11th to 20th	Night	63% 2 9% 17% 7% 1	3288
	21st to end	Night	74% 2 7% 13% 4	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	22% 20% 35% 18% 4 1	180
	11th to 20th	Day	29% 17% 33% 18% 3	180
	21st to end	Day	19% 17% 37% 22% 4	238
February	1st to 10th	Day	29% 21% 33% 14% 3	270
	11th to 20th	Day	29% 26% 36% 8% 1	270
	21st to end	Day	32% 19% 32% 14% 2	376
March	1st to 10th	Day	28% 16% 33% 19% 3 1	460
	11th to 20th	Day	27% 17% 34% 18% 3 1	460
	21st to end	Day	33% 16% 28% 16% 6% 1	506
April	1st to 10th	Day	32% 17% 29% 15% 5% 1	460
	11th to 20th	Day	35% 14% 25% 14% 10% 2	452
	21st to end	Day	32% 16% 30% 14% 7% 1	460
May	1st to 10th	Day	25% 12% 32% 20% 7% 3	463
	11th to 20th	Day	20% 14% 31% 22% 10% 3	487
	21st to end	Day	19% 13% 32% 22% 13% 1	529
June	1st to 10th	Day	25% 9% 31% 23% 9% 2	490
	11th to 20th	Day	16% 12% 31% 26% 12% 3	490
	21st to end	Day	22% 10% 30% 24% 11% 3	490
July	1st to 10th	Day	13% 5% 28% 34% 16% 4	485
	11th to 20th	Day	13% 6% 32% 29% 15% 5%	484
	21st to end	Day	14% 6% 29% 30% 16% 4	532
August	1st to 10th	Day	15% 5% 26% 31% 18% 5%	486
	11th to 20th	Day	14% 4 24% 30% 18% 9%	479
	21st to end	Day	16% 9% 27% 24% 15% 8%	539
September	1st to 10th	Day	17% 9% 28% 21% 16% 9%	490
	11th to 20th	Day	13% 6% 24% 24% 20% 12%	490
	21st to end	Day	18% 10% 30% 22% 16% 5%	490
October	1st to 10th	Day	23% 12% 25% 20% 14% 5%	490
	11th to 20th	Day	28% 16% 27% 19% 8% 2	490
	21st to end	Day	31% 14% 26% 22% 6%	464
November	1st to 10th	Day	28% 14% 30% 20% 8% 1	374
	11th to 20th	Day	31% 17% 32% 13% 6% 2	180
	21st to end	Day	29% 18% 36% 12% 5% 1	180
December	1st to 10th	Day	33% 11% 38% 16% 3	180
	11th to 20th	Day	31% 23% 34% 9% 3	180
	21st to end	Day	29% 21% 35% 11% 4 1	198
January	1st to 10th	Night	28% 13% 34% 21% 5%	760
	11th to 20th	Night	28% 16% 27% 22% 7% 1	760
	21st to end	Night	20% 11% 35% 28% 6%	836
February	1st to 10th	Night	23% 14% 34% 24% 4	760
	11th to 20th	Night	21% 15% 38% 21% 4	743
	21st to end	Night	26% 16% 28% 26% 4	628
March	1st to 10th	Night	24% 13% 33% 26% 4	760
	11th to 20th	Night	25% 15% 32% 22% 6%	760
	21st to end	Night	24% 15% 27% 26% 8%	836
April	1st to 10th	Night	27% 13% 30% 25% 6%	760
	11th to 20th	Night	26% 15% 28% 22% 8%	751
	21st to end	Night	26% 10% 29% 26% 8%	640
May	1st to 10th	Night	23% 7% 27% 32% 10% 1	380
	11th to 20th	Night	22% 8% 29% 31% 9% 1	374
	21st to end	Night	15% 5% 37% 29% 14%	411
June	1st to 10th	Night	17% 4 31% 36% 12%	380
	11th to 20th	Night	17% 6% 24% 36% 14% 1	380
	21st to end	Night	22% 4 26% 34% 14% 1	380
July	1st to 10th	Night	10% 4 28% 41% 17% 1	370
	11th to 20th	Night	14% 3 22% 46% 15% 1	368
	21st to end	Night	11% 4 22% 45% 17% 2	416
August	1st to 10th	Night	12% 3 20% 43% 22%	429
	11th to 20th	Night	12% 3 16% 40% 26% 3	564
	21st to end	Night	12% 5% 23% 38% 20% 2	833
September	1st to 10th	Night	14% 4 28% 33% 19% 2	760
	11th to 20th	Night	17% 4 20% 32% 22% 4	760
	21st to end	Night	20% 6% 23% 28% 20% 2	760
October	1st to 10th	Night	22% 9% 23% 28% 16% 2	760
	11th to 20th	Night	27% 10% 27% 27% 8% 1	760
	21st to end	Night	28% 12% 27% 26% 6%	836
November	1st to 10th	Night	27% 11% 25% 28% 9% 1	760
	11th to 20th	Night	25% 14% 32% 18% 9% 1	760
	21st to end	Night	31% 13% 26% 23% 7%	760
December	1st to 10th	Night	30% 13% 30% 22% 5%	760
	11th to 20th	Night	28% 15% 28% 22% 5% 1	760
	21st to end	Night	35% 12% 28% 20% 4	836

Page generated at 2024-11-03 02:11:08. Version ac07

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