Ritter Butte
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ritter Butte clear sky chart from 2005-11-06 to 2024-01-12.

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	11% 10% 4 6% 5% 3 4 4 5% 6% 43%	74784
	Night	12% 11% 4 6% 5% 3 4 4 5% 6% 41%	74942
Transparency	Day	43% 6% 10% 19% 16% 6%	74487
	Night	45% 6% 11% 18% 14% 5%	74760
Seeing	Day	14% 12% 26% 26% 16% 5%	13372
	Night	17% 7% 17% 35% 21% 3	22629

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	18% 15% 6% 8% 6% 3 6% 5% 4 7% 21%	1519
	11th to 20th	Day	16% 13% 4 8% 4 3 5% 5% 5% 6% 30%	1448
	21st to end	Day	13% 14% 4 7% 7% 3 5% 4 5% 8% 30%	1584
February	1st to 10th	Day	16% 16% 6% 8% 6% 3 5% 4 4 6% 26%	1602
	11th to 20th	Day	14% 18% 6% 8% 6% 3 5% 5% 5% 6% 26%	1668
	21st to end	Day	12% 17% 9% 9% 6% 3 4 5% 5% 6% 23%	1480
March	1st to 10th	Day	12% 16% 6% 10% 7% 4 6% 5% 5% 5% 24%	1800
	11th to 20th	Day	11% 16% 5% 8% 7% 3 6% 6% 5% 6% 26%	1867
	21st to end	Day	12% 19% 7% 11% 8% 4 6% 5% 4 4 19%	2362
April	1st to 10th	Day	13% 18% 6% 8% 6% 3 5% 4 5% 7% 26%	2160
	11th to 20th	Day	11% 12% 6% 8% 6% 4 5% 4 5% 7% 32%	2129
	21st to end	Day	13% 14% 4 8% 5% 3 4 4 4 6% 34%	2276
May	1st to 10th	Day	9% 10% 3 6% 6% 3 5% 5% 6% 7% 40%	2463
	11th to 20th	Day	14% 7% 3 7% 7% 4 5% 5% 6% 8% 35%	2477
	21st to end	Day	16% 10% 3 6% 5% 4 4 4 5% 7% 35%	2723
June	1st to 10th	Day	16% 7% 3 5% 5% 3 5% 5% 5% 6% 40%	2520
	11th to 20th	Day	12% 8% 3 5% 5% 3 3 4 5% 7% 45%	2520
	21st to end	Day	6% 4 1 3 3 2 3 4 4 6% 64%	2520
July	1st to 10th	Day	2 2 1 2 3 2 4 4 4 5% 71%	2520
	11th to 20th	Day	2 2 1 1 2 2 3 3 3 6% 74%	2520
	21st to end	Day	1 1 1 2 2 1 2 3 3 6% 78%	2741
August	1st to 10th	Day	3 2 1 3 3 2 3 3 4 6% 70%	2507
	11th to 20th	Day	3 2 1 3 2 2 2 3 3 6% 74%	2249
	21st to end	Day	3 3 2 3 2 1 2 3 4 6% 71%	2376
September	1st to 10th	Day	4 2 1 2 2 2 3 2 4 6% 72%	2160
	11th to 20th	Day	7% 4 2 4 3 2 3 4 5% 6% 59%	2111
	21st to end	Day	9% 7% 2 5% 4 2 3 4 5% 5% 53%	1980
October	1st to 10th	Day	14% 9% 3 6% 4 2 3 3 3 6% 47%	1842
	11th to 20th	Day	14% 7% 2 4 4 3 4 3 6% 8% 46%	1800
	21st to end	Day	16% 10% 3 7% 6% 3 3 4 4 5% 39%	1783
November	1st to 10th	Day	18% 13% 3 6% 5% 3 4 4 6% 9% 28%	1674
	11th to 20th	Day	16% 14% 5% 8% 7% 4 5% 5% 5% 7% 24%	1641
	21st to end	Day	15% 15% 5% 7% 5% 3 4 4 5% 6% 32%	1520
December	1st to 10th	Day	13% 16% 4 6% 5% 3 4 5% 4 7% 32%	1520
	11th to 20th	Day	12% 18% 4 8% 7% 3 4 5% 6% 6% 26%	1928
	21st to end	Day	13% 17% 7% 9% 7% 4 5% 4 5% 6% 24%	2794
January	1st to 10th	Night	18% 17% 6% 9% 6% 3 5% 4 5% 5% 22%	2646
	11th to 20th	Night	19% 15% 5% 6% 5% 2 4 3 3 7% 31%	2540
	21st to end	Night	15% 16% 4 7% 5% 3 4 5% 5% 6% 29%	2772
February	1st to 10th	Night	17% 16% 5% 8% 6% 3 4 4 5% 5% 27%	2354
	11th to 20th	Night	14% 20% 5% 8% 4 3 4 4 4 5% 29%	2177
	21st to end	Night	12% 20% 7% 9% 6% 4 4 4 4 7% 24%	1776
March	1st to 10th	Night	14% 14% 6% 8% 5% 3 5% 5% 6% 7% 27%	2160
	11th to 20th	Night	13% 15% 4 7% 7% 4 5% 6% 5% 7% 28%	2088
	21st to end	Night	13% 18% 6% 9% 7% 4 6% 4 6% 6% 22%	1994
April	1st to 10th	Night	13% 15% 5% 7% 6% 4 5% 4 4 7% 31%	1800
	11th to 20th	Night	13% 13% 4 7% 5% 3 4 3 4 7% 37%	1779
	21st to end	Night	12% 13% 3 6% 5% 4 5% 4 5% 7% 37%	1683
May	1st to 10th	Night	9% 9% 3 5% 5% 3 4 5% 4 6% 46%	1494
	11th to 20th	Night	12% 6% 2 5% 5% 3 6% 5% 5% 10% 43%	1416
	21st to end	Night	14% 9% 3 6% 5% 4 5% 4 4 8% 39%	1552
June	1st to 10th	Night	13% 7% 2 4 5% 3 4 5% 5% 8% 45%	1440
	11th to 20th	Night	15% 7% 3 4 4 2 4 4 4 7% 48%	1440
	21st to end	Night	5% 3 1 2 4 2 4 3 5% 6% 65%	1440
July	1st to 10th	Night	2 2 1 2 3 2 3 2 5% 6% 72%	1440
	11th to 20th	Night	1 1 2 2 1 2 3 4 5% 79%	1440
	21st to end	Night	1 1 1 1 2 1 3 3 3 5% 78%	1576
August	1st to 10th	Night	3 3 1 2 2 2 3 4 5% 8% 68%	1432
	11th to 20th	Night	2 2 1 2 2 2 3 3 4 5% 76%	1650
	21st to end	Night	3 3 1 2 3 1 2 3 4 4 74%	1980
September	1st to 10th	Night	4 2 1 2 2 2 1 2 4 6% 74%	1800
	11th to 20th	Night	5% 4 1 3 3 2 4 4 4 6% 62%	1849
	21st to end	Night	9% 7% 2 4 4 2 3 3 4 6% 55%	1980
October	1st to 10th	Night	12% 7% 3 4 4 3 3 4 5% 6% 51%	2114
	11th to 20th	Night	13% 8% 2 5% 4 3 4 4 4 6% 48%	2160
	21st to end	Night	15% 11% 3 7% 4 3 4 3 4 5% 41%	2571
November	1st to 10th	Night	19% 12% 3 6% 6% 3 5% 4 4 6% 32%	2405
	11th to 20th	Night	20% 13% 4 6% 6% 3 4 5% 5% 5% 30%	2536
	21st to end	Night	14% 15% 4 6% 4 2 5% 5% 5% 6% 34%	2660
December	1st to 10th	Night	15% 13% 5% 6% 5% 2 5% 5% 5% 7% 31%	2660
	11th to 20th	Night	14% 17% 5% 8% 6% 4 5% 5% 6% 7% 24%	3276
	21st to end	Night	15% 16% 6% 7% 6% 3 4 5% 5% 5% 28%	4862

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	63% 9% 12% 13% 3 1	1519
	11th to 20th	Day	54% 8% 11% 15% 9% 3	1448
	21st to end	Day	53% 8% 14% 15% 7% 2	1584
February	1st to 10th	Day	61% 8% 11% 14% 6%	1602
	11th to 20th	Day	61% 7% 11% 13% 7% 1	1677
	21st to end	Day	64% 7% 9% 12% 7% 1	1480
March	1st to 10th	Day	62% 7% 13% 11% 6% 1	1800
	11th to 20th	Day	59% 7% 10% 18% 6%	1867
	21st to end	Day	70% 6% 9% 12% 3	2362
April	1st to 10th	Day	60% 6% 12% 14% 6% 1	2160
	11th to 20th	Day	55% 6% 12% 15% 10% 2	2132
	21st to end	Day	53% 6% 10% 19% 12% 1	2276
May	1st to 10th	Day	43% 7% 12% 25% 12% 1	2463
	11th to 20th	Day	49% 7% 11% 23% 9% 1	2480
	21st to end	Day	51% 8% 12% 20% 8% 1	2724
June	1st to 10th	Day	47% 6% 11% 25% 10%	2520
	11th to 20th	Day	40% 6% 11% 26% 14% 3	2520
	21st to end	Day	24% 4 10% 28% 26% 8%	2520
July	1st to 10th	Day	16% 4 9% 22% 27% 22%	2451
	11th to 20th	Day	14% 4 8% 13% 31% 30%	2445
	21st to end	Day	11% 3 5% 12% 40% 29%	2589
August	1st to 10th	Day	17% 4 8% 21% 34% 17%	2490
	11th to 20th	Day	15% 3 7% 22% 36% 17%	2249
	21st to end	Day	16% 4 7% 24% 33% 15%	2376
September	1st to 10th	Day	17% 3 6% 24% 31% 19%	2160
	11th to 20th	Day	27% 5% 9% 21% 26% 12%	2111
	21st to end	Day	34% 5% 9% 22% 22% 8%	1980
October	1st to 10th	Day	41% 4 10% 20% 20% 5%	1842
	11th to 20th	Day	38% 6% 12% 22% 18% 3	1800
	21st to end	Day	49% 5% 10% 19% 16% 1	1783
November	1st to 10th	Day	54% 6% 13% 17% 9% 1	1674
	11th to 20th	Day	59% 8% 11% 17% 6%	1641
	21st to end	Day	55% 6% 10% 15% 13% 2	1520
December	1st to 10th	Day	53% 8% 14% 14% 8% 2	1520
	11th to 20th	Day	57% 9% 16% 12% 6%	1928
	21st to end	Day	60% 6% 13% 16% 4	2794
January	1st to 10th	Night	64% 8% 10% 13% 4 1	2646
	11th to 20th	Night	56% 5% 10% 14% 11% 4	2540
	21st to end	Night	56% 7% 11% 16% 9% 2	2772
February	1st to 10th	Night	61% 8% 11% 13% 7%	2354
	11th to 20th	Night	59% 6% 11% 14% 6% 3	2179
	21st to end	Night	62% 6% 9% 14% 8% 2	1776
March	1st to 10th	Night	56% 7% 11% 17% 7% 2	2160
	11th to 20th	Night	55% 8% 13% 19% 4 1	2088
	21st to end	Night	63% 8% 11% 15% 3	1994
April	1st to 10th	Night	55% 7% 11% 20% 6% 1	1800
	11th to 20th	Night	50% 7% 12% 20% 9% 2	1779
	21st to end	Night	48% 8% 13% 16% 14% 1	1683
May	1st to 10th	Night	39% 7% 14% 27% 13% 1	1494
	11th to 20th	Night	41% 7% 17% 25% 9% 1	1416
	21st to end	Night	48% 7% 16% 20% 9%	1552
June	1st to 10th	Night	40% 8% 13% 27% 12%	1440
	11th to 20th	Night	38% 6% 13% 28% 11% 4	1440
	21st to end	Night	22% 5% 13% 29% 23% 7%	1440
July	1st to 10th	Night	14% 5% 13% 23% 26% 20%	1400
	11th to 20th	Night	9% 4 11% 18% 33% 25%	1392
	21st to end	Night	11% 3 5% 17% 41% 23%	1488
August	1st to 10th	Night	16% 4 10% 23% 34% 14%	1424
	11th to 20th	Night	14% 3 7% 24% 35% 18%	1650
	21st to end	Night	15% 3 7% 25% 35% 13%	1980
September	1st to 10th	Night	15% 3 8% 26% 32% 17%	1800
	11th to 20th	Night	23% 5% 8% 25% 25% 14%	1849
	21st to end	Night	31% 4 10% 23% 23% 9%	1980
October	1st to 10th	Night	36% 5% 9% 23% 22% 5%	2114
	11th to 20th	Night	39% 5% 11% 19% 22% 5%	2160
	21st to end	Night	46% 6% 11% 16% 18% 3	2571
November	1st to 10th	Night	53% 7% 9% 18% 11% 2	2405
	11th to 20th	Night	56% 7% 10% 17% 10%	2536
	21st to end	Night	51% 7% 9% 14% 17% 2	2660
December	1st to 10th	Night	52% 9% 13% 14% 9% 2	2660
	11th to 20th	Night	58% 8% 13% 13% 7% 1	3276
	21st to end	Night	56% 8% 13% 16% 7% 1	4862

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	25% 22% 22% 17% 12% 3	180
	11th to 20th	Day	18% 18% 28% 20% 12% 4	162
	21st to end	Day	19% 15% 27% 22% 16% 1	176
February	1st to 10th	Day	25% 20% 27% 19% 7% 2	322
	11th to 20th	Day	24% 20% 25% 20% 10% 2	377
	21st to end	Day	22% 21% 26% 23% 7% 1	346
March	1st to 10th	Day	20% 17% 35% 22% 6% 1	420
	11th to 20th	Day	17% 19% 27% 26% 9% 1	420
	21st to end	Day	23% 15% 34% 21% 6% 1	462
April	1st to 10th	Day	22% 19% 23% 23% 9% 3	420
	11th to 20th	Day	19% 20% 29% 17% 10% 4	412
	21st to end	Day	17% 19% 24% 26% 12% 2	420
May	1st to 10th	Day	12% 17% 28% 25% 15% 3	423
	11th to 20th	Day	24% 12% 23% 22% 14% 6%	448
	21st to end	Day	17% 9% 25% 23% 20% 6%	485
June	1st to 10th	Day	18% 9% 23% 24% 18% 8%	450
	11th to 20th	Day	13% 17% 29% 24% 14% 3	450
	21st to end	Day	5% 7% 28% 34% 20% 7%	450
July	1st to 10th	Day	4 5% 30% 38% 20% 4	446
	11th to 20th	Day	2 7% 31% 34% 20% 6%	444
	21st to end	Day	1 6% 31% 33% 22% 7%	487
August	1st to 10th	Day	5% 5% 24% 36% 21% 8%	447
	11th to 20th	Day	3 3 21% 33% 25% 15%	437
	21st to end	Day	5% 7% 23% 34% 20% 9%	495
September	1st to 10th	Day	5% 5% 24% 33% 25% 9%	450
	11th to 20th	Day	8% 7% 24% 32% 23% 6%	450
	21st to end	Day	13% 8% 26% 27% 20% 6%	450
October	1st to 10th	Day	16% 10% 21% 27% 18% 8%	450
	11th to 20th	Day	15% 14% 23% 24% 17% 8%	450
	21st to end	Day	21% 13% 23% 22% 15% 5%	298
November	1st to 10th	Day	19% 17% 26% 24% 12% 1	270
	11th to 20th	Day	19% 15% 24% 24% 14% 3	237
	21st to end	Day	22% 8% 27% 30% 10% 3	180
December	1st to 10th	Day	20% 19% 20% 23% 11% 8%	180
	11th to 20th	Day	27% 15% 34% 15% 9%	180
	21st to end	Day	22% 14% 30% 22% 11% 1	198
January	1st to 10th	Night	24% 12% 24% 24% 15% 2	760
	11th to 20th	Night	26% 10% 18% 25% 18% 2	726
	21st to end	Night	24% 7% 16% 35% 16% 2	792
February	1st to 10th	Night	25% 8% 23% 32% 11% 2	720
	11th to 20th	Night	22% 9% 19% 31% 17% 2	704
	21st to end	Night	20% 14% 23% 31% 10% 2	592
March	1st to 10th	Night	20% 11% 24% 31% 13% 2	720
	11th to 20th	Night	18% 8% 23% 33% 16% 2	720
	21st to end	Night	21% 10% 21% 33% 14% 1	792
April	1st to 10th	Night	19% 12% 17% 34% 17% 2	720
	11th to 20th	Night	18% 8% 23% 29% 18% 4	711
	21st to end	Night	19% 8% 19% 33% 19% 2	603
May	1st to 10th	Night	13% 7% 17% 38% 22% 2	414
	11th to 20th	Night	15% 4 13% 33% 31% 5%	354
	21st to end	Night	19% 7% 11% 30% 29% 4	389
June	1st to 10th	Night	15% 5% 13% 40% 23% 4	360
	11th to 20th	Night	16% 5% 15% 40% 22% 2	360
	21st to end	Night	6% 2 11% 46% 34% 2	360
July	1st to 10th	Night	3 1 9% 52% 32% 3	350
	11th to 20th	Night	3 10% 59% 28% 1	348
	21st to end	Night	1 9% 51% 36% 3	394
August	1st to 10th	Night	3 1 5% 46% 42% 3	358
	11th to 20th	Night	2 1 7% 36% 44% 9%	582
	21st to end	Night	5% 3 11% 44% 33% 4	792
September	1st to 10th	Night	6% 2 10% 41% 38% 4	720
	11th to 20th	Night	7% 3 9% 37% 36% 9%	720
	21st to end	Night	12% 4 12% 37% 28% 7%	720
October	1st to 10th	Night	16% 3 11% 40% 26% 4	720
	11th to 20th	Night	16% 5% 17% 35% 21% 6%	720
	21st to end	Night	18% 9% 16% 34% 17% 5%	792
November	1st to 10th	Night	23% 8% 19% 35% 14% 1	740
	11th to 20th	Night	25% 8% 19% 31% 14% 2	760
	21st to end	Night	20% 9% 20% 31% 16% 5%	760
December	1st to 10th	Night	21% 9% 20% 31% 16% 2	760
	11th to 20th	Night	25% 9% 23% 29% 13% 1	760
	21st to end	Night	28% 11% 27% 24% 9% 1	836

Page generated at 2024-01-09 04:14:45. Version ac07

Copyright 2024 Attilla Danko