Ghost Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ghost Ranch clear sky chart from 2005-11-06 to 2024-11-25.

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	2 4 2 5% 4 4 5% 4 6% 8% 56%	105076
	Night	2 4 2 5% 4 4 4 4 6% 8% 56%	103135
Transparency	Day	22% 7% 11% 23% 24% 13%	104834
	Night	22% 7% 11% 23% 25% 12%	102966
Seeing	Day	10% 12% 25% 29% 19% 5%	15241
	Night	7% 7% 21% 41% 22% 2	25382

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% 4 6% 4 4 5% 5% 7% 9% 50%	2767
	11th to 20th	Day	1 5% 3 6% 3 3 3 4 5% 9% 58%	2860
	21st to end	Day	2 6% 2 8% 6% 5% 5% 5% 6% 8% 47%	3146
February	1st to 10th	Day	1 6% 3 7% 3 3 4 4 5% 7% 56%	1710
	11th to 20th	Day	1 5% 2 8% 5% 3 4 5% 6% 8% 54%	1822
	21st to end	Day	1 7% 2 6% 3 4 4 4 6% 8% 54%	1570
March	1st to 10th	Day	1 5% 2 4 4 3 3 3 6% 8% 60%	3322
	11th to 20th	Day	3 8% 3 7% 4 5% 5% 4 6% 9% 47%	3490
	21st to end	Day	1 6% 2 5% 4 5% 5% 4 6% 7% 54%	3933
April	1st to 10th	Day	2 4 1 3 3 4 4 4 6% 7% 62%	2280
	11th to 20th	Day	2 4 1 4 4 4 4 4 5% 8% 60%	2251
	21st to end	Day	2 5% 1 3 4 3 4 4 6% 9% 59%	2280
May	1st to 10th	Day	2 3 1 4 3 4 4 3 5% 6% 66%	3800
	11th to 20th	Day	3 4 2 5% 4 6% 6% 5% 7% 8% 50%	4078
	21st to end	Day	2 2 1 3 2 4 3 3 5% 6% 69%	4825
June	1st to 10th	Day	2 2 1 3 3 4 4 4 7% 8% 62%	2660
	11th to 20th	Day	1 1 1 2 2 3 3 3 5% 7% 70%	2660
	21st to end	Day	3 3 2 4 4 4 5% 5% 7% 7% 58%	2660
July	1st to 10th	Day	2 2 1 4 4 5% 5% 5% 6% 7% 58%	4407
	11th to 20th	Day	1 2 1 4 4 6% 8% 8% 11% 10% 46%	4110
	21st to end	Day	3 3 2 5% 5% 6% 7% 7% 10% 12% 41%	4454
August	1st to 10th	Day	2 3 1 6% 6% 7% 8% 7% 10% 12% 37%	4070
	11th to 20th	Day	2 3 1 4 4 4 6% 5% 8% 9% 53%	3726
	21st to end	Day	3 4 2 5% 5% 6% 8% 6% 9% 10% 41%	4180
September	1st to 10th	Day	5% 4 2 5% 4 5% 5% 4 6% 8% 53%	2280
	11th to 20th	Day	4 4 1 4 3 4 4 4 6% 7% 58%	2280
	21st to end	Day	2 3 1 3 3 3 4 3 5% 6% 67%	2047
October	1st to 10th	Day	2 2 1 3 3 3 3 3 4 7% 69%	3170
	11th to 20th	Day	4 3 2 5% 4 4 4 3 5% 7% 59%	3150
	21st to end	Day	3 2 1 3 2 3 3 3 4 5% 72%	3438
November	1st to 10th	Day	2 3 1 3 3 2 3 3 4 7% 69%	1899
	11th to 20th	Day	1 2 1 3 2 2 2 2 5% 7% 71%	1800
	21st to end	Day	2 5% 2 4 4 4 4 3 5% 6% 61%	1711
December	1st to 10th	Day	2 4 3 4 4 3 4 3 4 6% 62%	1520
	11th to 20th	Day	2 6% 2 6% 4 3 4 4 6% 9% 53%	1926
	21st to end	Day	2 6% 2 6% 4 3 3 4 6% 7% 57%	2794
January	1st to 10th	Night	1 5% 4 10% 5% 4 4 3 5% 10% 48%	4216
	11th to 20th	Night	1 5% 2 5% 5% 4 5% 4 6% 7% 54%	4110
	21st to end	Night	2 7% 3 7% 5% 5% 6% 4 6% 11% 45%	4521
February	1st to 10th	Night	1 5% 2 6% 3 3 3 3 5% 9% 61%	2470
	11th to 20th	Night	3 7% 2 5% 3 3 3 4 6% 7% 57%	2243
	21st to end	Night	2 5% 2 5% 4 4 3 3 5% 7% 61%	1884
March	1st to 10th	Night	1 5% 1 3 3 2 3 4 4 8% 66%	3532
	11th to 20th	Night	4 8% 2 7% 5% 4 5% 4 6% 8% 48%	3490
	21st to end	Night	2 5% 2 6% 4 4 5% 4 5% 7% 55%	3715
April	1st to 10th	Night	1 4 1 3 4 3 4 4 6% 8% 60%	1900
	11th to 20th	Night	2 6% 1 3 3 3 3 3 6% 7% 62%	1877
	21st to end	Night	2 4 1 3 3 3 4 4 6% 6% 62%	1900
May	1st to 10th	Night	3 4 1 4 3 3 3 3 4 6% 67%	3170
	11th to 20th	Night	4 4 2 6% 5% 5% 6% 6% 8% 7% 48%	2820
	21st to end	Night	2 2 1 3 3 3 3 2 5% 6% 71%	2762
June	1st to 10th	Night	1 2 1 3 2 3 4 3 7% 10% 62%	1520
	11th to 20th	Night	2 2 1 3 2 2 3 3 6% 6% 72%	1520
	21st to end	Night	3 3 2 3 3 4 5% 5% 8% 8% 54%	1520
July	1st to 10th	Night	2 2 1 5% 5% 6% 5% 5% 7% 7% 55%	2558
	11th to 20th	Night	1 2 1 5% 5% 6% 8% 7% 13% 12% 39%	2860
	21st to end	Night	5% 5% 2 6% 5% 6% 6% 6% 9% 11% 39%	3109
August	1st to 10th	Night	5% 5% 2 9% 6% 7% 8% 7% 10% 10% 31%	2868
	11th to 20th	Night	2 3 2 6% 5% 5% 6% 6% 9% 12% 42%	3113
	21st to end	Night	4 4 2 7% 6% 8% 8% 7% 11% 10% 33%	3487
September	1st to 10th	Night	4 3 2 5% 5% 5% 5% 5% 7% 9% 51%	1900
	11th to 20th	Night	4 3 1 4 3 3 4 3 5% 9% 62%	1900
	21st to end	Night	4 4 2 4 2 3 3 3 4 6% 67%	2128
October	1st to 10th	Night	2 2 1 3 2 2 2 2 4 6% 72%	3800
	11th to 20th	Night	5% 3 2 5% 3 4 3 3 5% 6% 62%	3778
	21st to end	Night	2 1 1 2 2 2 3 2 4 6% 75%	4120
November	1st to 10th	Night	1 3 1 2 2 2 2 3 4 7% 72%	2378
	11th to 20th	Night	2 1 2 2 2 2 2 5% 6% 74%	2600
	21st to end	Night	3 6% 2 4 3 3 3 3 5% 8% 62%	2562
December	1st to 10th	Night	2 5% 2 4 3 4 4 3 5% 8% 61%	2660
	11th to 20th	Night	2 5% 2 5% 4 4 5% 4 8% 11% 50%	3271
	21st to end	Night	2 6% 3 7% 4 4 4 3 6% 9% 52%	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	22% 11% 13% 29% 24% 1	2768
	11th to 20th	Day	20% 7% 18% 37% 16% 2	2860
	21st to end	Day	31% 10% 10% 27% 20% 3	3146
February	1st to 10th	Day	26% 6% 12% 28% 21% 7%	1710
	11th to 20th	Day	28% 4 9% 27% 25% 7%	1832
	21st to end	Day	27% 5% 7% 19% 29% 12%	1570
March	1st to 10th	Day	20% 6% 6% 25% 37% 6%	3322
	11th to 20th	Day	28% 9% 11% 29% 19% 5%	3490
	21st to end	Day	25% 8% 7% 27% 27% 6%	3933
April	1st to 10th	Day	20% 5% 9% 24% 28% 15%	2280
	11th to 20th	Day	22% 6% 6% 21% 30% 15%	2254
	21st to end	Day	22% 5% 8% 24% 30% 11%	2280
May	1st to 10th	Day	14% 8% 7% 17% 32% 21%	3800
	11th to 20th	Day	23% 12% 11% 21% 22% 11%	4081
	21st to end	Day	13% 7% 6% 14% 33% 28%	4825
June	1st to 10th	Day	18% 5% 11% 21% 25% 20%	2660
	11th to 20th	Day	13% 4 6% 15% 26% 36%	2660
	21st to end	Day	22% 7% 9% 19% 23% 20%	2660
July	1st to 10th	Day	22% 7% 9% 12% 18% 30%	4338
	11th to 20th	Day	24% 10% 16% 34% 11% 5%	4041
	21st to end	Day	29% 10% 21% 26% 9% 5%	4314
August	1st to 10th	Day	33% 12% 21% 19% 9% 6%	4056
	11th to 20th	Day	23% 8% 17% 20% 17% 15%	3762
	21st to end	Day	31% 11% 18% 21% 16% 4	4179
September	1st to 10th	Day	28% 6% 11% 23% 21% 12%	2280
	11th to 20th	Day	24% 6% 10% 17% 28% 15%	2280
	21st to end	Day	18% 4 7% 21% 36% 14%	2047
October	1st to 10th	Day	16% 4 6% 16% 34% 24%	3170
	11th to 20th	Day	23% 7% 5% 19% 33% 13%	3150
	21st to end	Day	14% 5% 5% 23% 39% 14%	3438
November	1st to 10th	Day	16% 3 7% 25% 36% 13%	1899
	11th to 20th	Day	13% 3 9% 30% 37% 8%	1800
	21st to end	Day	24% 3 5% 26% 31% 10%	1711
December	1st to 10th	Day	22% 5% 14% 31% 21% 8%	1520
	11th to 20th	Day	27% 6% 13% 26% 24% 4	1924
	21st to end	Day	24% 5% 10% 24% 27% 10%	2794
January	1st to 10th	Night	26% 9% 10% 29% 22% 3	4216
	11th to 20th	Night	20% 11% 15% 34% 16% 4	4110
	21st to end	Night	28% 8% 11% 30% 20% 3	4521
February	1st to 10th	Night	21% 4 14% 29% 24% 7%	2470
	11th to 20th	Night	25% 6% 8% 28% 26% 7%	2243
	21st to end	Night	23% 5% 6% 22% 35% 10%	1884
March	1st to 10th	Night	16% 5% 6% 24% 41% 8%	3532
	11th to 20th	Night	28% 9% 9% 27% 22% 5%	3490
	21st to end	Night	21% 12% 7% 28% 27% 5%	3715
April	1st to 10th	Night	20% 6% 9% 23% 28% 14%	1900
	11th to 20th	Night	21% 5% 6% 21% 31% 17%	1877
	21st to end	Night	19% 6% 8% 22% 31% 13%	1900
May	1st to 10th	Night	15% 9% 6% 14% 32% 23%	3170
	11th to 20th	Night	25% 12% 13% 22% 15% 14%	2821
	21st to end	Night	10% 8% 7% 13% 29% 33%	2762
June	1st to 10th	Night	17% 6% 13% 18% 24% 22%	1520
	11th to 20th	Night	13% 4 6% 12% 28% 37%	1520
	21st to end	Night	24% 8% 10% 15% 19% 24%	1520
July	1st to 10th	Night	26% 9% 10% 11% 13% 32%	2518
	11th to 20th	Night	27% 9% 23% 27% 7% 6%	2806
	21st to end	Night	33% 10% 21% 25% 10% 2	3011
August	1st to 10th	Night	41% 12% 19% 13% 7% 7%	2859
	11th to 20th	Night	30% 9% 22% 13% 11% 16%	3143
	21st to end	Night	36% 13% 17% 16% 12% 5%	3487
September	1st to 10th	Night	27% 7% 14% 21% 18% 13%	1900
	11th to 20th	Night	20% 7% 12% 16% 23% 22%	1900
	21st to end	Night	18% 5% 8% 18% 33% 18%	2128
October	1st to 10th	Night	15% 4 6% 15% 36% 24%	3800
	11th to 20th	Night	22% 6% 6% 17% 31% 18%	3778
	21st to end	Night	11% 3 5% 25% 37% 19%	4120
November	1st to 10th	Night	12% 4 6% 27% 38% 13%	2378
	11th to 20th	Night	12% 3 7% 31% 38% 10%	2600
	21st to end	Night	22% 4 7% 23% 32% 12%	2562
December	1st to 10th	Night	21% 5% 10% 33% 26% 5%	2660
	11th to 20th	Night	25% 7% 11% 28% 25% 3	3272
	21st to end	Night	25% 6% 10% 25% 29% 4	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	11% 15% 31% 29% 12% 2	270
	11th to 20th	Day	16% 14% 28% 28% 12% 2	270
	21st to end	Day	7% 11% 28% 35% 15% 5%	297
February	1st to 10th	Day	12% 19% 26% 32% 10% 1	270
	11th to 20th	Day	10% 19% 31% 30% 10%	270
	21st to end	Day	22% 19% 29% 23% 5% 1	225
March	1st to 10th	Day	15% 22% 30% 22% 10% 1	384
	11th to 20th	Day	19% 20% 27% 22% 9% 3	460
	21st to end	Day	23% 23% 32% 15% 6% 1	506
April	1st to 10th	Day	15% 26% 30% 19% 9% 1	460
	11th to 20th	Day	15% 30% 31% 17% 6% 1	452
	21st to end	Day	14% 24% 36% 20% 6%	460
May	1st to 10th	Day	13% 22% 36% 19% 9% 1	463
	11th to 20th	Day	10% 15% 32% 26% 14% 4	530
	21st to end	Day	9% 14% 28% 30% 17% 2	734
June	1st to 10th	Day	4 8% 24% 34% 28% 3	680
	11th to 20th	Day	4 9% 28% 31% 23% 4	680
	21st to end	Day	6% 5% 24% 33% 27% 5%	680
July	1st to 10th	Day	4 5% 15% 34% 34% 8%	661
	11th to 20th	Day	2 2 11% 33% 36% 15%	484
	21st to end	Day	5% 3 10% 31% 35% 16%	531
August	1st to 10th	Day	4 5% 12% 34% 31% 14%	487
	11th to 20th	Day	6% 5% 16% 34% 31% 9%	477
	21st to end	Day	6% 3 14% 37% 30% 11%	539
September	1st to 10th	Day	7% 4 17% 33% 30% 9%	490
	11th to 20th	Day	6% 7% 21% 37% 20% 9%	490
	21st to end	Day	4 9% 22% 31% 23% 11%	342
October	1st to 10th	Day	7% 10% 22% 28% 25% 8%	300
	11th to 20th	Day	10% 13% 23% 25% 19% 10%	300
	21st to end	Day	12% 11% 24% 28% 18% 6%	330
November	1st to 10th	Day	10% 13% 29% 29% 17% 3	300
	11th to 20th	Day	7% 9% 28% 34% 18% 4	300
	21st to end	Day	13% 11% 31% 22% 15% 8%	282
December	1st to 10th	Day	14% 11% 29% 27% 15% 4	270
	11th to 20th	Day	11% 14% 27% 29% 17% 2	270
	21st to end	Day	16% 20% 25% 29% 9% 1	297
January	1st to 10th	Night	6% 9% 24% 42% 17% 2	827
	11th to 20th	Night	6% 8% 26% 40% 18% 2	760
	21st to end	Night	6% 9% 25% 42% 16% 2	836
February	1st to 10th	Night	8% 9% 28% 42% 12% 1	760
	11th to 20th	Night	8% 10% 31% 39% 11% 1	744
	21st to end	Night	9% 11% 37% 37% 7%	628
March	1st to 10th	Night	6% 10% 32% 41% 10% 1	760
	11th to 20th	Night	9% 8% 24% 43% 15% 1	760
	21st to end	Night	10% 11% 31% 37% 11%	774
April	1st to 10th	Night	8% 14% 34% 36% 8%	570
	11th to 20th	Night	10% 14% 27% 36% 12%	563
	21st to end	Night	6% 13% 30% 42% 9%	570
May	1st to 10th	Night	8% 7% 29% 42% 14%	570
	11th to 20th	Night	7% 5% 25% 41% 19% 2	561
	21st to end	Night	4 8% 28% 43% 17% 1	617
June	1st to 10th	Night	3 4 17% 50% 25% 1	570
	11th to 20th	Night	3 4 22% 51% 20% 1	570
	21st to end	Night	4 3 13% 44% 34% 1	570
July	1st to 10th	Night	3 3 7% 43% 42% 2	555
	11th to 20th	Night	4 1 3 33% 53% 7%	552
	21st to end	Night	5% 2 3 26% 54% 10%	624
August	1st to 10th	Night	4 3 5% 25% 51% 11%	567
	11th to 20th	Night	4 3 4 39% 44% 5%	564
	21st to end	Night	4 3 4 38% 46% 5%	627
September	1st to 10th	Night	5% 1 6% 44% 39% 5%	570
	11th to 20th	Night	6% 2 9% 47% 34% 3	570
	21st to end	Night	6% 3 14% 43% 31% 3	651
October	1st to 10th	Night	6% 3 17% 48% 23% 2	760
	11th to 20th	Night	5% 5% 19% 46% 21% 4	760
	21st to end	Night	7% 5% 21% 39% 23% 5%	836
November	1st to 10th	Night	3 5% 21% 49% 19% 3	818
	11th to 20th	Night	5% 7% 24% 43% 18% 3	1000
	21st to end	Night	9% 9% 22% 37% 20% 3	973
December	1st to 10th	Night	8% 9% 28% 40% 13% 1	950
	11th to 20th	Night	10% 11% 25% 37% 15% 1	950
	21st to end	Night	10% 11% 28% 39% 10% 1	1045

Page generated at 2024-11-22 06:02:25. Version ac07

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