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 2024-01-14.

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 4 4 3 5% 5% 6% 8% 57%	74700
	Night	2 4 2 4 4 3 4 5% 6% 8% 59%	75077
Transparency	Day	24% 6% 11% 23% 25% 12%	74421
	Night	22% 6% 11% 24% 26% 11%	74877
Seeing	Day	9% 12% 24% 29% 19% 6%	14038
	Night	6% 7% 21% 41% 22% 3	24285

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 4 2 4 4 3 4 5% 7% 9% 56%	1656
	11th to 20th	Day	2 5% 3 5% 4 2 2 4 4 9% 61%	1647
	21st to end	Day	2 5% 2 5% 5% 3 4 4 5% 7% 58%	1782
February	1st to 10th	Day	1 5% 3 5% 4 2 4 5% 5% 7% 59%	1620
	11th to 20th	Day	2 4 2 7% 6% 3 4 6% 5% 8% 54%	1724
	21st to end	Day	1 7% 3 6% 4 2 5% 5% 6% 8% 54%	1480
March	1st to 10th	Day	2 5% 3 4 5% 3 4 5% 7% 9% 54%	1908
	11th to 20th	Day	2 6% 3 6% 5% 3 5% 5% 5% 7% 55%	1980
	21st to end	Day	2 4 3 3 5% 4 6% 5% 6% 8% 54%	2235
April	1st to 10th	Day	2 4 1 3 3 2 4 4 6% 8% 62%	2160
	11th to 20th	Day	2 4 2 4 4 3 5% 5% 5% 8% 59%	2131
	21st to end	Day	2 4 2 3 4 2 4 5% 6% 9% 59%	2160
May	1st to 10th	Day	2 3 1 3 4 2 5% 4 6% 8% 62%	2160
	11th to 20th	Day	3 4 2 4 5% 3 5% 6% 6% 8% 54%	2292
	21st to end	Day	2 3 1 3 3 3 4 4 6% 7% 63%	2724
June	1st to 10th	Day	2 2 1 2 4 3 5% 5% 7% 9% 62%	2520
	11th to 20th	Day	1 1 1 2 3 2 4 4 6% 7% 70%	2520
	21st to end	Day	3 2 2 3 4 2 5% 6% 7% 8% 60%	2520
July	1st to 10th	Day	3 3 2 4 6% 5% 6% 7% 7% 10% 48%	2511
	11th to 20th	Day	1 3 1 3 6% 4 7% 8% 9% 11% 47%	2340
	21st to end	Day	4 3 2 5% 7% 4 8% 9% 10% 13% 34%	2545
August	1st to 10th	Day	3 3 2 5% 7% 5% 7% 8% 7% 11% 41%	2319
	11th to 20th	Day	3 4 2 4 5% 4 6% 8% 8% 9% 47%	2123
	21st to end	Day	3 3 2 3 5% 3 5% 7% 8% 9% 51%	2376
September	1st to 10th	Day	6% 3 2 4 5% 4 5% 6% 6% 8% 52%	2160
	11th to 20th	Day	4 4 1 4 4 3 4 5% 5% 7% 58%	2160
	21st to end	Day	2 3 2 3 3 3 4 4 5% 5% 66%	1940
October	1st to 10th	Day	4 3 2 5% 4 3 5% 4 6% 8% 57%	1800
	11th to 20th	Day	2 2 1 2 3 1 2 2 4 5% 75%	1800
	21st to end	Day	3 3 1 2 3 2 3 3 3 5% 70%	1980
November	1st to 10th	Day	1 2 1 3 3 2 3 3 4 7% 72%	1802
	11th to 20th	Day	1 2 2 3 2 2 3 3 5% 7% 71%	1710
	21st to end	Day	2 5% 2 4 4 3 4 4 4 6% 61%	1675
December	1st to 10th	Day	2 4 3 4 4 2 4 4 4 6% 62%	1520
	11th to 20th	Day	2 6% 3 6% 5% 2 4 5% 6% 9% 53%	1926
	21st to end	Day	2 6% 2 5% 4 2 3 5% 6% 7% 57%	2794
January	1st to 10th	Night	1 4 2 5% 3 2 4 4 5% 9% 60%	2524
	11th to 20th	Night	2 6% 2 3 4 2 4 4 5% 8% 61%	2391
	21st to end	Night	2 5% 3 5% 4 2 4 4 5% 9% 57%	2574
February	1st to 10th	Night	1 5% 2 4 4 2 3 3 5% 10% 63%	2340
	11th to 20th	Night	3 6% 3 4 4 3 3 4 6% 7% 57%	2121
	21st to end	Night	2 6% 2 5% 4 3 3 4 4 6% 62%	1776
March	1st to 10th	Night	2 4 2 4 4 2 4 6% 5% 8% 62%	2048
	11th to 20th	Night	3 6% 2 4 4 2 4 3 4 8% 59%	1980
	21st to end	Night	3 4 2 4 4 2 4 5% 5% 7% 60%	2120
April	1st to 10th	Night	2 3 1 3 4 2 4 5% 7% 8% 61%	1800
	11th to 20th	Night	2 5% 2 3 4 2 3 4 6% 7% 61%	1777
	21st to end	Night	3 3 2 3 3 3 4 5% 6% 7% 63%	1800
May	1st to 10th	Night	3 3 2 4 4 2 3 4 4 7% 64%	1800
	11th to 20th	Night	4 4 2 4 5% 3 5% 6% 6% 7% 53%	1596
	21st to end	Night	2 1 1 3 3 2 4 3 6% 8% 67%	1552
June	1st to 10th	Night	1 2 1 2 3 2 5% 4 6% 11% 63%	1440
	11th to 20th	Night	2 2 2 2 2 1 3 3 5% 6% 73%	1440
	21st to end	Night	3 2 1 3 3 3 6% 6% 7% 9% 56%	1440
July	1st to 10th	Night	2 3 2 5% 6% 4 8% 6% 9% 9% 45%	1444
	11th to 20th	Night	2 2 1 4 6% 4 7% 8% 10% 11% 46%	1620
	21st to end	Night	3 4 2 6% 7% 5% 7% 8% 10% 13% 36%	1773
August	1st to 10th	Night	4 3 1 5% 4 3 7% 6% 7% 11% 48%	1619
	11th to 20th	Night	3 4 2 5% 7% 4 6% 8% 9% 10% 41%	1778
	21st to end	Night	3 3 2 4 6% 4 7% 7% 9% 9% 47%	1980
September	1st to 10th	Night	4 3 1 4 6% 3 6% 6% 6% 10% 50%	1800
	11th to 20th	Night	4 3 1 3 3 2 4 4 5% 9% 61%	1800
	21st to end	Night	4 4 2 3 3 2 3 3 4 6% 66%	2015
October	1st to 10th	Night	4 3 2 3 4 2 4 4 5% 7% 62%	2160
	11th to 20th	Night	2 1 1 2 2 2 2 2 3 5% 77%	2160
	21st to end	Night	4 2 1 2 2 3 3 3 4 7% 70%	2376
November	1st to 10th	Night	1 2 1 1 2 1 3 3 4 7% 75%	2256
	11th to 20th	Night	2 1 2 3 2 2 3 5% 6% 74%	2470
	21st to end	Night	3 5% 2 4 3 2 3 3 5% 7% 62%	2503
December	1st to 10th	Night	2 5% 2 4 3 3 4 4 5% 8% 61%	2660
	11th to 20th	Night	2 5% 2 4 5% 3 5% 5% 7% 11% 50%	3271
	21st to end	Night	2 6% 3 6% 5% 3 5% 4 5% 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	21% 7% 11% 34% 25% 2	1657
	11th to 20th	Day	23% 3 12% 35% 23% 3	1647
	21st to end	Day	26% 5% 9% 30% 24% 5%	1782
February	1st to 10th	Day	26% 5% 12% 28% 22% 7%	1620
	11th to 20th	Day	29% 4 9% 27% 24% 7%	1734
	21st to end	Day	27% 5% 8% 20% 29% 12%	1480
March	1st to 10th	Day	26% 6% 8% 22% 30% 9%	1908
	11th to 20th	Day	27% 5% 8% 23% 28% 8%	1980
	21st to end	Day	27% 6% 7% 24% 28% 8%	2235
April	1st to 10th	Day	19% 5% 9% 25% 28% 15%	2160
	11th to 20th	Day	23% 6% 6% 21% 30% 14%	2134
	21st to end	Day	22% 5% 8% 24% 30% 11%	2160
May	1st to 10th	Day	21% 4 7% 22% 33% 13%	2160
	11th to 20th	Day	28% 7% 11% 20% 25% 9%	2295
	21st to end	Day	19% 6% 9% 18% 27% 20%	2724
June	1st to 10th	Day	18% 5% 11% 21% 25% 20%	2520
	11th to 20th	Day	13% 4 7% 15% 26% 36%	2520
	21st to end	Day	20% 6% 9% 20% 24% 21%	2520
July	1st to 10th	Day	30% 9% 14% 13% 17% 18%	2442
	11th to 20th	Day	26% 9% 19% 24% 13% 8%	2271
	21st to end	Day	35% 12% 24% 21% 6% 1	2404
August	1st to 10th	Day	35% 11% 16% 13% 14% 10%	2304
	11th to 20th	Day	30% 8% 15% 20% 17% 9%	2123
	21st to end	Day	26% 7% 16% 24% 21% 7%	2376
September	1st to 10th	Day	29% 6% 12% 22% 20% 11%	2160
	11th to 20th	Day	24% 6% 10% 17% 28% 15%	2160
	21st to end	Day	19% 4 7% 20% 36% 14%	1940
October	1st to 10th	Day	25% 6% 10% 21% 23% 16%	1800
	11th to 20th	Day	14% 3 4 17% 40% 22%	1800
	21st to end	Day	17% 4 8% 25% 36% 10%	1980
November	1st to 10th	Day	14% 3 7% 26% 36% 13%	1802
	11th to 20th	Day	14% 3 9% 31% 37% 7%	1710
	21st to end	Day	25% 3 5% 26% 32% 9%	1675
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	21% 5% 12% 31% 28% 3	2524
	11th to 20th	Night	22% 4 12% 34% 24% 5%	2391
	21st to end	Night	24% 5% 9% 32% 25% 5%	2574
February	1st to 10th	Night	20% 4 14% 30% 25% 7%	2340
	11th to 20th	Night	26% 6% 9% 27% 26% 7%	2121
	21st to end	Night	23% 5% 6% 22% 35% 9%	1776
March	1st to 10th	Night	20% 6% 7% 27% 30% 10%	2048
	11th to 20th	Night	23% 6% 7% 26% 29% 9%	1980
	21st to end	Night	22% 7% 7% 23% 33% 8%	2120
April	1st to 10th	Night	20% 6% 9% 24% 28% 14%	1800
	11th to 20th	Night	22% 4 6% 22% 30% 16%	1777
	21st to end	Night	20% 6% 8% 23% 31% 13%	1800
May	1st to 10th	Night	21% 5% 6% 18% 35% 15%	1800
	11th to 20th	Night	28% 9% 11% 18% 23% 11%	1597
	21st to end	Night	15% 7% 10% 20% 26% 22%	1552
June	1st to 10th	Night	17% 5% 14% 19% 24% 21%	1440
	11th to 20th	Night	13% 4 6% 12% 28% 37%	1440
	21st to end	Night	23% 7% 10% 15% 20% 25%	1440
July	1st to 10th	Night	31% 12% 15% 13% 11% 18%	1404
	11th to 20th	Night	27% 9% 22% 19% 11% 11%	1566
	21st to end	Night	33% 13% 27% 20% 5% 1	1674
August	1st to 10th	Night	27% 12% 21% 17% 11% 12%	1610
	11th to 20th	Night	34% 9% 19% 16% 12% 11%	1778
	21st to end	Night	27% 10% 17% 20% 18% 8%	1980
September	1st to 10th	Night	28% 7% 15% 21% 17% 12%	1800
	11th to 20th	Night	20% 7% 12% 16% 23% 22%	1800
	21st to end	Night	19% 5% 8% 17% 32% 19%	2015
October	1st to 10th	Night	22% 6% 10% 19% 24% 19%	2160
	11th to 20th	Night	12% 3 6% 16% 39% 24%	2160
	21st to end	Night	16% 3 6% 27% 34% 14%	2376
November	1st to 10th	Night	11% 4 6% 28% 39% 13%	2256
	11th to 20th	Night	12% 3 7% 32% 37% 9%	2470
	21st to end	Night	22% 4 7% 24% 32% 11%	2503
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	14% 13% 30% 30% 12% 2	249
	21st to end	Day	7% 12% 30% 35% 12% 4	264
February	1st to 10th	Day	9% 19% 26% 34% 11% 2	240
	11th to 20th	Day	10% 20% 30% 29% 10%	240
	21st to end	Day	20% 20% 31% 23% 5% 1	198
March	1st to 10th	Day	16% 22% 30% 22% 9% 1	348
	11th to 20th	Day	18% 20% 27% 22% 9% 4	420
	21st to end	Day	22% 24% 32% 15% 6% 1	462
April	1st to 10th	Day	15% 27% 29% 19% 9% 1	420
	11th to 20th	Day	16% 30% 30% 17% 6% 1	412
	21st to end	Day	15% 25% 36% 18% 6%	420
May	1st to 10th	Day	11% 22% 37% 20% 9% 1	423
	11th to 20th	Day	9% 16% 32% 27% 13% 4	487
	21st to end	Day	9% 13% 29% 31% 16% 2	679
June	1st to 10th	Day	4 8% 24% 34% 27% 3	630
	11th to 20th	Day	4 8% 27% 32% 24% 5%	630
	21st to end	Day	6% 4 24% 33% 28% 6%	630
July	1st to 10th	Day	4 5% 13% 34% 35% 9%	612
	11th to 20th	Day	3 2 12% 34% 34% 15%	444
	21st to end	Day	6% 3 9% 29% 36% 17%	487
August	1st to 10th	Day	4 6% 12% 34% 31% 13%	447
	11th to 20th	Day	6% 5% 17% 33% 30% 8%	437
	21st to end	Day	6% 3 14% 38% 29% 11%	495
September	1st to 10th	Day	7% 4 17% 33% 29% 10%	450
	11th to 20th	Day	6% 6% 20% 38% 21% 9%	450
	21st to end	Day	4 9% 23% 30% 22% 11%	310
October	1st to 10th	Day	7% 11% 23% 27% 24% 7%	270
	11th to 20th	Day	10% 12% 24% 25% 19% 10%	270
	21st to end	Day	12% 11% 25% 28% 19% 6%	297
November	1st to 10th	Day	10% 11% 27% 31% 16% 4	270
	11th to 20th	Day	6% 8% 27% 34% 20% 5%	270
	21st to end	Day	13% 11% 31% 22% 14% 8%	270
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% 7% 26% 40% 18% 2	736
	21st to end	Night	6% 9% 26% 42% 15% 2	792
February	1st to 10th	Night	7% 8% 28% 43% 13% 1	720
	11th to 20th	Night	9% 10% 30% 39% 11% 1	704
	21st to end	Night	8% 11% 36% 38% 7%	592
March	1st to 10th	Night	6% 10% 32% 41% 10% 2	720
	11th to 20th	Night	8% 8% 24% 43% 16% 1	720
	21st to end	Night	10% 11% 30% 38% 11%	734
April	1st to 10th	Night	7% 14% 34% 37% 8%	540
	11th to 20th	Night	10% 14% 26% 37% 13%	533
	21st to end	Night	6% 13% 31% 41% 9%	540
May	1st to 10th	Night	7% 6% 28% 43% 15%	540
	11th to 20th	Night	7% 5% 25% 41% 20% 2	531
	21st to end	Night	4 7% 27% 43% 17% 1	584
June	1st to 10th	Night	3 4 17% 49% 26% 1	540
	11th to 20th	Night	3 4 20% 51% 21% 1	540
	21st to end	Night	4 2 13% 44% 35% 1	540
July	1st to 10th	Night	3 3 5% 43% 43% 2	525
	11th to 20th	Night	3 1 2 33% 54% 7%	522
	21st to end	Night	5% 2 3 24% 56% 10%	591
August	1st to 10th	Night	4 2 5% 26% 52% 11%	537
	11th to 20th	Night	4 3 4 38% 44% 5%	534
	21st to end	Night	4 3 4 37% 47% 5%	594
September	1st to 10th	Night	6% 1 6% 44% 39% 5%	540
	11th to 20th	Night	6% 2 6% 47% 35% 3	540
	21st to end	Night	6% 3 14% 42% 31% 3	616
October	1st to 10th	Night	6% 3 18% 47% 23% 2	720
	11th to 20th	Night	4 5% 19% 47% 21% 4	720
	21st to end	Night	8% 5% 20% 39% 23% 5%	792
November	1st to 10th	Night	3 5% 20% 49% 20% 3	776
	11th to 20th	Night	5% 6% 23% 43% 19% 3	950
	21st to end	Night	10% 9% 21% 36% 21% 3	950
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 2024-01-11 11:32:00. Version ac07

Copyright 2024 Attilla Danko