Fort Phil Kearny Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Phil Kearny Observatory clear sky chart from 2005-11-06 to 2024-11-11.

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	5% 5% 2 5% 4 4 5% 4 7% 8% 52%	105501
	Night	3 5% 2 5% 4 4 4 4 6% 8% 55%	102406
Transparency	Day	26% 9% 16% 24% 18% 6%	105244
	Night	23% 10% 17% 27% 17% 6%	102253
Seeing	Day	8% 12% 33% 31% 14% 3	15909
	Night	6% 10% 35% 36% 13% 2	25935

By Month

Percentage Cloud Cover SW (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	1 5% 3 7% 5% 5% 6% 5% 7% 8% 49%	2538
	11th to 20th	Day	2 2 6% 3 4 5% 5% 9% 11% 53%	2540
	21st to end	Day	1 2 1 4 3 3 4 4 6% 8% 62%	3059
February	1st to 10th	Day	1 6% 3 9% 7% 5% 7% 4 7% 8% 42%	1710
	11th to 20th	Day	1 6% 4 8% 5% 5% 5% 5% 7% 8% 46%	1665
	21st to end	Day	2 5% 2 8% 5% 5% 5% 6% 7% 9% 45%	1542
March	1st to 10th	Day	1 5% 2 6% 4 4 4 4 6% 9% 55%	3216
	11th to 20th	Day	3 6% 2 5% 4 4 4 4 6% 9% 54%	3490
	21st to end	Day	6% 12% 5% 10% 5% 4 4 4 7% 11% 32%	3965
April	1st to 10th	Day	6% 11% 2 6% 5% 5% 5% 5% 7% 8% 41%	2280
	11th to 20th	Day	7% 9% 4 9% 4 5% 4 4 7% 9% 38%	2251
	21st to end	Day	11% 10% 2 7% 4 4 5% 4 7% 10% 38%	2381
May	1st to 10th	Day	12% 11% 3 7% 5% 5% 5% 4 7% 7% 33%	4393
	11th to 20th	Day	8% 6% 2 5% 3 5% 5% 4 6% 9% 46%	4388
	21st to end	Day	10% 7% 2 5% 4 4 4 5% 8% 9% 42%	4825
June	1st to 10th	Day	7% 5% 1 4 3 4 6% 6% 10% 10% 44%	2660
	11th to 20th	Day	6% 4 2 4 4 5% 5% 5% 8% 10% 47%	2660
	21st to end	Day	3 2 1 3 3 4 5% 4 7% 9% 59%	2660
July	1st to 10th	Day	4 2 1 3 3 3 5% 5% 7% 8% 58%	4430
	11th to 20th	Day	1 1 2 2 4 6% 6% 9% 8% 60%	4430
	21st to end	Day	2 2 1 3 3 3 5% 4 8% 10% 59%	4802
August	1st to 10th	Day	7% 4 1 5% 4 5% 5% 5% 8% 8% 48%	4166
	11th to 20th	Day	3 2 1 4 3 5% 6% 4 8% 9% 54%	4028
	21st to end	Day	2 2 1 3 3 4 4 3 6% 8% 66%	4211
September	1st to 10th	Day	6% 3 1 4 3 3 3 3 6% 7% 62%	2280
	11th to 20th	Day	5% 4 1 3 3 3 3 3 5% 7% 62%	2280
	21st to end	Day	7% 5% 1 4 3 3 3 2 5% 6% 62%	2021
October	1st to 10th	Day	5% 4 2 3 2 2 2 2 3 4 71%	3170
	11th to 20th	Day	7% 5% 2 3 2 2 3 3 4 5% 64%	3150
	21st to end	Day	5% 6% 2 7% 4 3 3 3 5% 8% 54%	3290
November	1st to 10th	Day	2 5% 2 5% 3 5% 4 4 7% 8% 54%	1740
	11th to 20th	Day	2 4 3 3 4 5% 5% 4 7% 9% 55%	1520
	21st to end	Day	3 5% 2 4 4 4 4 5% 7% 10% 53%	1520
December	1st to 10th	Day	1 4 2 5% 4 4 4 5% 9% 9% 53%	1520
	11th to 20th	Day	1 3 1 3 4 4 3 4 7% 8% 62%	1926
	21st to end	Day	2 4 2 4 3 5% 4 5% 7% 10% 54%	2794
January	1st to 10th	Night	1 4 3 8% 5% 5% 5% 5% 7% 9% 49%	4417
	11th to 20th	Night	3 3 9% 5% 6% 6% 5% 7% 8% 48%	4430
	21st to end	Night	1 4 2 6% 4 4 4 4 7% 8% 55%	4637
February	1st to 10th	Night	1 5% 2 10% 6% 6% 6% 5% 7% 10% 44%	2470
	11th to 20th	Night	1 7% 3 8% 5% 5% 5% 5% 7% 8% 45%	2402
	21st to end	Night	1 5% 2 7% 5% 5% 5% 5% 7% 8% 51%	1910
March	1st to 10th	Night	1 6% 2 6% 4 4 4 4 6% 9% 54%	3650
	11th to 20th	Night	3 7% 2 5% 4 4 4 4 5% 9% 55%	3490
	21st to end	Night	5% 9% 4 10% 6% 5% 5% 4 5% 9% 39%	3683
April	1st to 10th	Night	6% 9% 2 6% 4 4 5% 4 6% 8% 47%	1900
	11th to 20th	Night	5% 8% 4 6% 5% 4 4 5% 6% 8% 44%	1877
	21st to end	Night	6% 8% 2 6% 3 3 5% 3 7% 9% 49%	1796
May	1st to 10th	Night	10% 11% 3 5% 3 3 4 4 5% 7% 45%	2576
	11th to 20th	Night	8% 5% 1 4 3 3 5% 4 7% 11% 49%	2517
	21st to end	Night	9% 6% 2 5% 4 4 4 3 5% 10% 49%	2762
June	1st to 10th	Night	7% 4 2 4 4 4 3 5% 6% 9% 51%	1520
	11th to 20th	Night	7% 4 1 3 3 4 4 4 6% 8% 57%	1520
	21st to end	Night	3 3 1 3 2 2 3 3 6% 9% 64%	1520
July	1st to 10th	Night	2 1 1 2 2 3 4 4 6% 9% 67%	2540
	11th to 20th	Night	2 2 1 1 2 2 4 4 7% 10% 65%	2540
	21st to end	Night	2 2 1 3 3 3 4 3 6% 11% 62%	2761
August	1st to 10th	Night	6% 2 1 4 3 4 5% 5% 6% 10% 55%	2770
	11th to 20th	Night	3 3 1 3 4 3 5% 4 8% 10% 56%	2811
	21st to end	Night	2 2 1 3 2 2 3 3 5% 8% 70%	3455
September	1st to 10th	Night	4 4 1 3 2 2 3 2 4 7% 68%	1900
	11th to 20th	Night	5% 3 1 3 3 3 3 4 5% 6% 63%	1900
	21st to end	Night	6% 5% 1 3 3 2 3 2 3 6% 66%	2153
October	1st to 10th	Night	5% 5% 1 3 2 2 2 2 2 5% 72%	3800
	11th to 20th	Night	7% 4 1 3 3 2 2 3 4 6% 64%	3778
	21st to end	Night	2 5% 2 5% 3 4 4 3 5% 8% 58%	4235
November	1st to 10th	Night	3 5% 2 5% 4 4 4 4 7% 9% 53%	2555
	11th to 20th	Night	2 5% 2 5% 4 4 4 4 6% 7% 56%	2667
	21st to end	Night	3 7% 2 5% 3 4 4 4 5% 7% 56%	2660
December	1st to 10th	Night	1 4 2 5% 5% 6% 5% 5% 8% 10% 50%	2660
	11th to 20th	Night	2 3 1 5% 3 3 4 4 7% 9% 59%	3271
	21st to end	Night	2 5% 2 5% 4 4 4 4 6% 8% 54%	4873

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	26% 13% 17% 29% 14% 1	2539
	11th to 20th	Day	21% 11% 26% 25% 14% 3	2540
	21st to end	Day	18% 9% 21% 34% 16% 3	3059
February	1st to 10th	Day	37% 10% 17% 23% 10% 2	1710
	11th to 20th	Day	32% 11% 18% 22% 12% 4	1674
	21st to end	Day	31% 12% 17% 20% 15% 5%	1542
March	1st to 10th	Day	22% 8% 16% 23% 28% 3	3216
	11th to 20th	Day	26% 11% 25% 27% 10% 1	3490
	21st to end	Day	42% 16% 21% 18% 3	3965
April	1st to 10th	Day	40% 10% 19% 20% 10% 2	2280
	11th to 20th	Day	41% 9% 21% 19% 10% 1	2254
	21st to end	Day	42% 10% 18% 20% 9% 1	2381
May	1st to 10th	Day	45% 8% 17% 19% 9% 2	4393
	11th to 20th	Day	32% 11% 18% 22% 14% 2	4392
	21st to end	Day	33% 11% 20% 27% 9% 1	4825
June	1st to 10th	Day	29% 13% 22% 22% 12% 2	2660
	11th to 20th	Day	27% 12% 19% 19% 20% 3	2660
	21st to end	Day	18% 11% 16% 27% 20% 9%	2660
July	1st to 10th	Day	19% 7% 12% 28% 25% 8%	4361
	11th to 20th	Day	14% 8% 11% 23% 27% 16%	4355
	21st to end	Day	16% 8% 11% 22% 29% 14%	4651
August	1st to 10th	Day	28% 9% 13% 20% 20% 9%	4151
	11th to 20th	Day	21% 9% 12% 26% 25% 7%	4067
	21st to end	Day	15% 6% 11% 23% 34% 11%	4210
September	1st to 10th	Day	21% 6% 10% 21% 28% 13%	2280
	11th to 20th	Day	23% 6% 11% 27% 24% 9%	2280
	21st to end	Day	23% 6% 13% 27% 26% 6%	2021
October	1st to 10th	Day	20% 4 9% 18% 34% 15%	3170
	11th to 20th	Day	24% 5% 13% 25% 25% 7%	3150
	21st to end	Day	26% 8% 15% 32% 14% 4	3290
November	1st to 10th	Day	24% 12% 17% 22% 21% 4	1740
	11th to 20th	Day	24% 10% 20% 24% 18% 3	1520
	21st to end	Day	26% 8% 21% 25% 16% 4	1520
December	1st to 10th	Day	24% 12% 20% 25% 16% 4	1520
	11th to 20th	Day	18% 8% 24% 33% 14% 2	1924
	21st to end	Day	23% 9% 16% 30% 15% 7%	2794
January	1st to 10th	Night	26% 12% 16% 31% 12% 2	4417
	11th to 20th	Night	25% 9% 28% 21% 13% 4	4430
	21st to end	Night	23% 12% 19% 31% 13% 2	4637
February	1st to 10th	Night	32% 13% 19% 23% 10% 3	2470
	11th to 20th	Night	32% 12% 19% 20% 14% 3	2403
	21st to end	Night	28% 11% 16% 22% 17% 6%	1910
March	1st to 10th	Night	20% 10% 19% 25% 22% 5%	3650
	11th to 20th	Night	24% 11% 26% 24% 13% 2	3490
	21st to end	Night	30% 21% 25% 19% 5%	3683
April	1st to 10th	Night	34% 10% 19% 23% 11% 3	1900
	11th to 20th	Night	34% 11% 18% 26% 11% 1	1877
	21st to end	Night	30% 12% 18% 28% 12% 1	1796
May	1st to 10th	Night	36% 9% 15% 24% 16% 1	2576
	11th to 20th	Night	26% 12% 19% 31% 10% 2	2518
	21st to end	Night	28% 13% 21% 31% 6% 1	2762
June	1st to 10th	Night	27% 11% 24% 22% 14% 1	1520
	11th to 20th	Night	22% 12% 21% 24% 16% 4	1520
	21st to end	Night	16% 9% 16% 31% 23% 5%	1520
July	1st to 10th	Night	13% 7% 14% 34% 25% 6%	2500
	11th to 20th	Night	11% 7% 12% 29% 30% 10%	2492
	21st to end	Night	15% 7% 10% 24% 31% 13%	2674
August	1st to 10th	Night	21% 9% 16% 23% 21% 10%	2762
	11th to 20th	Night	20% 7% 14% 32% 19% 9%	2838
	21st to end	Night	13% 5% 10% 27% 28% 17%	3455
September	1st to 10th	Night	17% 5% 10% 23% 31% 14%	1900
	11th to 20th	Night	22% 6% 11% 27% 24% 10%	1900
	21st to end	Night	21% 6% 11% 28% 27% 7%	2153
October	1st to 10th	Night	19% 4 10% 22% 27% 17%	3800
	11th to 20th	Night	22% 5% 12% 29% 23% 9%	3778
	21st to end	Night	23% 7% 15% 31% 15% 8%	4235
November	1st to 10th	Night	25% 11% 18% 23% 18% 5%	2555
	11th to 20th	Night	24% 10% 16% 30% 16% 4	2667
	21st to end	Night	27% 8% 18% 25% 17% 6%	2660
December	1st to 10th	Night	24% 13% 19% 23% 16% 5%	2660
	11th to 20th	Night	19% 11% 20% 36% 12% 2	3272
	21st to end	Night	25% 8% 15% 28% 17% 6%	4873

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	4 10% 33% 32% 16% 4	270
	11th to 20th	Day	5% 14% 39% 24% 14% 4	270
	21st to end	Day	6% 18% 43% 23% 8% 3	297
February	1st to 10th	Day	6% 16% 54% 21% 2	270
	11th to 20th	Day	5% 16% 42% 31% 4	270
	21st to end	Day	4 19% 42% 28% 7%	225
March	1st to 10th	Day	3 21% 41% 28% 7%	317
	11th to 20th	Day	8% 19% 38% 24% 8% 2	460
	21st to end	Day	12% 17% 39% 22% 8% 2	506
April	1st to 10th	Day	16% 19% 40% 20% 5%	460
	11th to 20th	Day	13% 29% 34% 20% 4	452
	21st to end	Day	18% 14% 35% 25% 8% 1	460
May	1st to 10th	Day	14% 19% 24% 28% 13% 2	629
	11th to 20th	Day	16% 11% 29% 26% 15% 3	675
	21st to end	Day	15% 11% 29% 27% 15% 4	734
June	1st to 10th	Day	6% 10% 26% 34% 20% 4	680
	11th to 20th	Day	7% 13% 35% 31% 12% 1	680
	21st to end	Day	4 8% 31% 38% 16% 3	680
July	1st to 10th	Day	4 3 25% 39% 25% 3	671
	11th to 20th	Day	1 4 29% 44% 19% 2	668
	21st to end	Day	3 3 25% 40% 24% 5%	739
August	1st to 10th	Day	6% 4 30% 39% 17% 4	535
	11th to 20th	Day	4 6% 25% 41% 19% 4	477
	21st to end	Day	3 7% 29% 40% 18% 4	539
September	1st to 10th	Day	5% 8% 28% 39% 16% 4	490
	11th to 20th	Day	9% 6% 31% 34% 16% 3	490
	21st to end	Day	11% 11% 26% 32% 15% 4	358
October	1st to 10th	Day	10% 10% 27% 32% 15% 6%	300
	11th to 20th	Day	8% 19% 27% 28% 13% 4	300
	21st to end	Day	9% 15% 38% 26% 8% 2	330
November	1st to 10th	Day	6% 15% 40% 22% 14% 3	300
	11th to 20th	Day	8% 16% 36% 28% 11% 1	270
	21st to end	Day	8% 14% 40% 27% 9% 1	270
December	1st to 10th	Day	7% 16% 40% 23% 12% 1	270
	11th to 20th	Day	4 15% 51% 24% 5%	270
	21st to end	Day	4 16% 42% 25% 11% 1	297
January	1st to 10th	Night	3 11% 40% 33% 11% 2	950
	11th to 20th	Night	3 17% 44% 23% 10% 2	950
	21st to end	Night	4 15% 42% 29% 9% 1	900
February	1st to 10th	Night	3 12% 48% 28% 8% 1	760
	11th to 20th	Night	3 13% 42% 33% 8% 2	744
	21st to end	Night	4 12% 42% 30% 10% 2	628
March	1st to 10th	Night	3 11% 45% 31% 9% 2	760
	11th to 20th	Night	6% 9% 43% 30% 10% 2	760
	21st to end	Night	9% 12% 37% 29% 11% 1	755
April	1st to 10th	Night	10% 10% 40% 34% 5% 1	570
	11th to 20th	Night	8% 15% 38% 33% 6%	563
	21st to end	Night	11% 10% 30% 38% 9% 1	570
May	1st to 10th	Night	11% 10% 26% 36% 16% 1	570
	11th to 20th	Night	14% 8% 21% 37% 18% 1	561
	21st to end	Night	14% 6% 27% 37% 15%	617
June	1st to 10th	Night	8% 7% 28% 41% 15% 1	570
	11th to 20th	Night	8% 6% 36% 38% 11%	570
	21st to end	Night	4 6% 23% 49% 18% 1	570
July	1st to 10th	Night	4 2 18% 54% 20% 1	555
	11th to 20th	Night	2 2 21% 56% 18% 1	552
	21st to end	Night	2 2 16% 54% 24% 1	624
August	1st to 10th	Night	4 3 14% 56% 23% 1	567
	11th to 20th	Night	4 3 15% 50% 26% 3	564
	21st to end	Night	3 3 21% 48% 23% 2	627
September	1st to 10th	Night	5% 3 19% 50% 21% 2	570
	11th to 20th	Night	6% 5% 22% 46% 16% 4	570
	21st to end	Night	9% 7% 27% 38% 15% 4	693
October	1st to 10th	Night	12% 6% 31% 33% 15% 3	760
	11th to 20th	Night	8% 9% 33% 33% 14% 2	760
	21st to end	Night	5% 12% 36% 34% 11% 2	902
November	1st to 10th	Night	5% 12% 40% 32% 10% 1	975
	11th to 20th	Night	4 14% 44% 30% 7% 1	953
	21st to end	Night	7% 13% 40% 31% 8% 1	950
December	1st to 10th	Night	2 13% 44% 32% 8% 1	950
	11th to 20th	Night	3 10% 46% 32% 8% 1	950
	21st to end	Night	4 13% 42% 30% 8% 1	1045

Page generated at 2024-11-08 04:44:50. Version ac07

Copyright © 2024 Attilla Danko.