Asbestos
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Asbestos clear sky chart from 2005-11-06 to 2024-01-22.

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	21% 12% 4 7% 6% 3 4 4 5% 6% 28%	74602
	Night	20% 13% 5% 8% 6% 3 4 4 4 5% 28%	75308
Transparency	Day	58% 5% 11% 17% 8% 1	74308
	Night	59% 5% 10% 17% 8% 1	75137
Seeing	Day	28% 17% 28% 18% 7% 2	13566
	Night	27% 14% 27% 23% 8% 1	22672

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	21% 21% 8% 14% 7% 4 4 4 3 3 12%	1517
	11th to 20th	Day	20% 17% 7% 15% 8% 3 5% 3 2 3 18%	1520
	21st to end	Day	12% 17% 6% 11% 9% 3 6% 5% 4 5% 21%	1592
February	1st to 10th	Day	16% 19% 8% 12% 9% 4 5% 4 3 4 17%	1485
	11th to 20th	Day	16% 20% 9% 11% 7% 4 5% 3 3 4 18%	1742
	21st to end	Day	15% 18% 6% 11% 7% 5% 4 4 4 5% 21%	1480
March	1st to 10th	Day	16% 15% 5% 11% 8% 4 5% 4 4 4 24%	1797
	11th to 20th	Day	18% 15% 6% 8% 6% 4 5% 3 4 5% 27%	1864
	21st to end	Day	18% 16% 5% 8% 6% 3 4 4 3 3 29%	2342
April	1st to 10th	Day	23% 15% 5% 9% 6% 3 4 4 4 3 24%	2160
	11th to 20th	Day	22% 11% 3 5% 6% 2 3 3 4 6% 34%	2177
	21st to end	Day	26% 11% 4 7% 5% 3 4 4 4 6% 27%	2340
May	1st to 10th	Day	24% 9% 3 6% 6% 3 4 3 4 6% 32%	2389
	11th to 20th	Day	20% 8% 4 5% 6% 3 5% 4 4 8% 34%	2478
	21st to end	Day	20% 7% 3 6% 6% 3 5% 6% 6% 7% 29%	2725
June	1st to 10th	Day	27% 7% 3 5% 5% 3 4 5% 6% 8% 28%	2520
	11th to 20th	Day	20% 6% 3 5% 5% 3 5% 5% 6% 8% 35%	2520
	21st to end	Day	24% 8% 3 7% 7% 3 5% 5% 5% 7% 27%	2520
July	1st to 10th	Day	19% 6% 3 6% 5% 4 5% 4 6% 8% 34%	2520
	11th to 20th	Day	17% 6% 4 6% 5% 4 6% 5% 7% 9% 32%	2520
	21st to end	Day	19% 7% 2 6% 5% 4 5% 5% 7% 9% 31%	2744
August	1st to 10th	Day	20% 7% 3 7% 6% 3 4 6% 6% 9% 30%	2498
	11th to 20th	Day	17% 7% 3 6% 6% 3 4 5% 6% 9% 34%	2304
	21st to end	Day	20% 5% 2 6% 5% 3 4 5% 6% 8% 36%	2404
September	1st to 10th	Day	18% 6% 3 6% 5% 2 5% 4 6% 8% 37%	2160
	11th to 20th	Day	21% 5% 2 4 4 3 3 5% 5% 6% 42%	2019
	21st to end	Day	22% 6% 2 5% 4 3 4 4 6% 8% 35%	1980
October	1st to 10th	Day	25% 9% 3 5% 4 4 4 4 5% 8% 29%	1956
	11th to 20th	Day	25% 12% 3 7% 5% 4 5% 5% 5% 6% 25%	1684
	21st to end	Day	29% 16% 3 6% 5% 3 4 3 3 6% 21%	1782
November	1st to 10th	Day	22% 15% 4 6% 6% 2 4 4 3 5% 29%	1671
	11th to 20th	Day	21% 17% 7% 8% 6% 3 3 4 4 6% 22%	1710
	21st to end	Day	21% 21% 5% 8% 5% 3 3 5% 4 4 19%	1535
December	1st to 10th	Day	26% 20% 7% 10% 7% 3 4 3 3 4 13%	1388
	11th to 20th	Day	22% 17% 8% 7% 6% 4 4 3 3 3 23%	1787
	21st to end	Day	26% 19% 6% 12% 5% 3 4 2 2 3 18%	2772
January	1st to 10th	Night	20% 20% 8% 11% 7% 4 4 4 3 4 14%	2649
	11th to 20th	Night	17% 18% 7% 13% 8% 4 5% 4 3 3 18%	2660
	21st to end	Night	12% 16% 6% 12% 9% 5% 6% 4 4 4 22%	2798
February	1st to 10th	Night	16% 16% 7% 12% 8% 4 5% 4 3 4 20%	2470
	11th to 20th	Night	15% 18% 6% 12% 8% 4 5% 4 3 4 21%	2102
	21st to end	Night	16% 15% 6% 9% 8% 4 5% 4 4 4 26%	1776
March	1st to 10th	Night	17% 16% 6% 9% 7% 3 4 3 4 5% 26%	2150
	11th to 20th	Night	20% 14% 6% 7% 5% 3 4 4 3 4 28%	2094
	21st to end	Night	19% 14% 5% 8% 5% 3 4 4 4 4 32%	2012
April	1st to 10th	Night	25% 12% 5% 8% 5% 3 4 4 4 4 27%	1800
	11th to 20th	Night	22% 10% 3 6% 4 3 3 3 4 6% 33%	1732
	21st to end	Night	25% 11% 3 6% 4 3 4 4 5% 5% 30%	1620
May	1st to 10th	Night	24% 10% 3 7% 4 2 4 4 3 6% 30%	1586
	11th to 20th	Night	20% 10% 3 5% 5% 3 4 5% 4 6% 35%	1415
	21st to end	Night	21% 6% 2 5% 5% 3 5% 5% 6% 7% 35%	1550
June	1st to 10th	Night	26% 7% 3 6% 5% 3 4 5% 7% 7% 28%	1440
	11th to 20th	Night	22% 5% 2 4 5% 3 4 5% 6% 8% 35%	1440
	21st to end	Night	20% 7% 3 6% 6% 3 6% 6% 5% 7% 31%	1440
July	1st to 10th	Night	16% 6% 2 5% 6% 3 5% 4 6% 9% 37%	1440
	11th to 20th	Night	14% 5% 2 6% 6% 4 6% 6% 6% 9% 36%	1440
	21st to end	Night	15% 6% 3 7% 5% 3 5% 5% 6% 8% 36%	1574
August	1st to 10th	Night	17% 5% 2 6% 5% 3 5% 5% 7% 8% 38%	1432
	11th to 20th	Night	18% 7% 2 6% 7% 3 4 4 5% 7% 37%	1587
	21st to end	Night	18% 7% 3 5% 4 4 5% 4 6% 8% 38%	1949
September	1st to 10th	Night	20% 6% 2 6% 5% 3 4 4 5% 6% 39%	1800
	11th to 20th	Night	19% 5% 2 5% 3 2 3 4 5% 7% 45%	1940
	21st to end	Night	22% 6% 2 4 5% 3 4 3 4 7% 41%	1980
October	1st to 10th	Night	22% 7% 3 5% 4 3 4 4 5% 6% 36%	2002
	11th to 20th	Night	24% 11% 3 6% 5% 3 4 4 5% 5% 28%	2275
	21st to end	Night	28% 12% 3 6% 5% 3 4 4 4 5% 26%	2574
November	1st to 10th	Night	22% 15% 4 8% 5% 3 4 4 5% 5% 27%	2407
	11th to 20th	Night	21% 14% 6% 7% 6% 2 4 4 4 4 28%	2470
	21st to end	Night	23% 17% 6% 8% 6% 3 3 3 4 5% 23%	2644
December	1st to 10th	Night	25% 21% 8% 10% 6% 3 4 3 3 4 14%	2782
	11th to 20th	Night	21% 20% 7% 12% 6% 3 4 3 2 4 18%	3394
	21st to end	Night	25% 20% 6% 10% 5% 3 3 3 3 3 19%	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	79% 4 7% 8% 2	1518
	11th to 20th	Day	74% 4 6% 11% 5% 1	1520
	21st to end	Day	66% 4 9% 14% 6% 1	1592
February	1st to 10th	Day	74% 3 7% 10% 5% 1	1485
	11th to 20th	Day	72% 4 8% 10% 5% 1	1751
	21st to end	Day	67% 4 7% 14% 6% 1	1480
March	1st to 10th	Day	64% 4 7% 15% 7% 2	1800
	11th to 20th	Day	61% 4 10% 13% 11% 1	1864
	21st to end	Day	61% 3 8% 16% 10% 2	2342
April	1st to 10th	Day	65% 5% 7% 14% 7% 2	2160
	11th to 20th	Day	54% 3 9% 20% 13% 1	2177
	21st to end	Day	59% 4 8% 15% 10% 2	2340
May	1st to 10th	Day	55% 3 8% 19% 12% 2	2389
	11th to 20th	Day	50% 5% 13% 20% 11% 1	2482
	21st to end	Day	53% 7% 11% 17% 12%	2725
June	1st to 10th	Day	55% 6% 11% 19% 7% 1	2520
	11th to 20th	Day	47% 7% 13% 22% 10% 1	2520
	21st to end	Day	58% 6% 11% 18% 8%	2520
July	1st to 10th	Day	46% 7% 15% 25% 7%	2450
	11th to 20th	Day	47% 7% 16% 23% 6%	2445
	21st to end	Day	49% 8% 15% 21% 6%	2591
August	1st to 10th	Day	51% 8% 17% 21% 3	2484
	11th to 20th	Day	46% 8% 18% 20% 8%	2304
	21st to end	Day	45% 8% 14% 22% 10%	2404
September	1st to 10th	Day	45% 6% 16% 23% 9% 1	2160
	11th to 20th	Day	43% 5% 13% 28% 11%	2019
	21st to end	Day	47% 7% 13% 24% 9%	1980
October	1st to 10th	Day	54% 5% 13% 20% 7%	1956
	11th to 20th	Day	60% 6% 14% 17% 3	1684
	21st to end	Day	67% 4 9% 14% 5% 1	1782
November	1st to 10th	Day	59% 4 13% 17% 7%	1671
	11th to 20th	Day	65% 4 11% 12% 7% 1	1710
	21st to end	Day	69% 5% 12% 12% 2	1535
December	1st to 10th	Day	77% 3 8% 8% 3	1388
	11th to 20th	Day	69% 4 7% 14% 6%	1788
	21st to end	Day	75% 3 7% 10% 5%	2772
January	1st to 10th	Night	75% 4 8% 9% 3	2649
	11th to 20th	Night	74% 4 7% 10% 4 1	2660
	21st to end	Night	65% 5% 10% 13% 6% 1	2798
February	1st to 10th	Night	69% 4 8% 12% 6% 1	2470
	11th to 20th	Night	69% 4 8% 12% 7%	2104
	21st to end	Night	63% 3 8% 15% 10% 1	1776
March	1st to 10th	Night	64% 4 8% 16% 8% 1	2160
	11th to 20th	Night	61% 4 9% 13% 12% 2	2095
	21st to end	Night	57% 4 7% 19% 9% 3	2012
April	1st to 10th	Night	61% 4 7% 15% 11% 1	1800
	11th to 20th	Night	52% 4 8% 21% 12% 2	1732
	21st to end	Night	56% 5% 10% 17% 10% 2	1620
May	1st to 10th	Night	55% 5% 7% 18% 14% 2	1586
	11th to 20th	Night	49% 7% 9% 19% 14% 2	1416
	21st to end	Night	47% 8% 11% 18% 14% 1	1551
June	1st to 10th	Night	53% 7% 12% 19% 9% 1	1440
	11th to 20th	Night	45% 7% 10% 23% 12% 2	1440
	21st to end	Night	51% 8% 12% 18% 10% 1	1440
July	1st to 10th	Night	43% 9% 16% 21% 11%	1400
	11th to 20th	Night	42% 9% 17% 22% 10%	1392
	21st to end	Night	45% 9% 15% 23% 8%	1486
August	1st to 10th	Night	42% 8% 19% 26% 6%	1422
	11th to 20th	Night	46% 7% 16% 23% 8%	1587
	21st to end	Night	44% 7% 15% 25% 9%	1949
September	1st to 10th	Night	46% 6% 14% 23% 11% 1	1800
	11th to 20th	Night	40% 4 16% 30% 10% 1	1940
	21st to end	Night	45% 6% 12% 25% 12% 1	1980
October	1st to 10th	Night	50% 5% 11% 23% 11%	2002
	11th to 20th	Night	57% 7% 12% 20% 4	2275
	21st to end	Night	61% 6% 11% 14% 8% 1	2574
November	1st to 10th	Night	59% 6% 12% 17% 6% 1	2407
	11th to 20th	Night	61% 4 11% 14% 7% 2	2470
	21st to end	Night	66% 4 12% 14% 4	2644
December	1st to 10th	Night	76% 4 9% 9% 2	2782
	11th to 20th	Night	73% 4 7% 11% 5%	3394
	21st to end	Night	71% 4 8% 14% 3	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	30% 24% 31% 13% 2	180
	11th to 20th	Day	33% 22% 30% 13% 2	180
	21st to end	Day	27% 24% 33% 12% 4 1	178
February	1st to 10th	Day	44% 28% 23% 5%	180
	11th to 20th	Day	32% 25% 31% 9% 2	410
	21st to end	Day	29% 28% 27% 14% 2	346
March	1st to 10th	Day	28% 23% 29% 16% 3	420
	11th to 20th	Day	30% 23% 28% 14% 5% 1	420
	21st to end	Day	30% 22% 26% 14% 6% 2	462
April	1st to 10th	Day	36% 18% 25% 14% 7%	420
	11th to 20th	Day	34% 19% 24% 14% 6% 2	412
	21st to end	Day	33% 21% 28% 12% 5% 1	420
May	1st to 10th	Day	32% 20% 28% 15% 5% 1	423
	11th to 20th	Day	26% 15% 34% 19% 5% 2	447
	21st to end	Day	23% 22% 31% 18% 6% 1	485
June	1st to 10th	Day	30% 18% 30% 16% 5% 1	450
	11th to 20th	Day	22% 19% 29% 21% 9%	450
	21st to end	Day	27% 13% 32% 18% 7% 2	450
July	1st to 10th	Day	21% 9% 34% 26% 10%	445
	11th to 20th	Day	18% 11% 36% 26% 8% 1	444
	21st to end	Day	23% 7% 35% 27% 7% 1	488
August	1st to 10th	Day	21% 11% 26% 27% 13% 2	446
	11th to 20th	Day	20% 8% 30% 25% 15% 2	439
	21st to end	Day	23% 14% 23% 21% 12% 6%	495
September	1st to 10th	Day	20% 12% 31% 20% 11% 6%	450
	11th to 20th	Day	22% 11% 23% 23% 14% 7%	450
	21st to end	Day	21% 14% 26% 25% 10% 5%	450
October	1st to 10th	Day	27% 16% 25% 20% 10% 3	450
	11th to 20th	Day	33% 17% 25% 15% 9% 1	392
	21st to end	Day	41% 16% 23% 16% 5%	396
November	1st to 10th	Day	35% 15% 28% 18% 3	365
	11th to 20th	Day	32% 21% 25% 16% 4 1	370
	21st to end	Day	34% 20% 31% 12% 3	195
December	1st to 10th	Day	37% 17% 27% 12% 6% 1	180
	11th to 20th	Day	38% 22% 29% 9% 1 1	180
	21st to end	Day	40% 26% 22% 10% 2 1	198
January	1st to 10th	Night	32% 20% 30% 16% 3	760
	11th to 20th	Night	28% 23% 29% 17% 4	760
	21st to end	Night	21% 21% 29% 24% 5%	800
February	1st to 10th	Night	26% 21% 30% 19% 4	720
	11th to 20th	Night	26% 22% 31% 17% 3	703
	21st to end	Night	26% 17% 32% 21% 3	592
March	1st to 10th	Night	28% 16% 33% 20% 3	720
	11th to 20th	Night	31% 18% 28% 18% 5%	720
	21st to end	Night	27% 16% 26% 23% 7% 1	792
April	1st to 10th	Night	33% 14% 25% 23% 5%	720
	11th to 20th	Night	29% 15% 27% 22% 6%	668
	21st to end	Night	32% 17% 27% 17% 6%	540
May	1st to 10th	Night	29% 10% 31% 21% 8% 1	506
	11th to 20th	Night	24% 11% 30% 29% 6% 1	354
	21st to end	Night	24% 12% 29% 28% 8%	389
June	1st to 10th	Night	28% 7% 28% 29% 8%	360
	11th to 20th	Night	21% 8% 26% 33% 12%	360
	21st to end	Night	21% 8% 27% 34% 11%	360
July	1st to 10th	Night	18% 5% 28% 36% 13% 1	350
	11th to 20th	Night	15% 4 28% 36% 14% 2	348
	21st to end	Night	16% 5% 26% 39% 14%	394
August	1st to 10th	Night	17% 6% 16% 42% 19% 1	358
	11th to 20th	Night	19% 4 21% 37% 18% 1	523
	21st to end	Night	21% 6% 22% 33% 17% 2	761
September	1st to 10th	Night	23% 6% 25% 33% 12% 2	720
	11th to 20th	Night	22% 6% 21% 30% 18% 2	720
	21st to end	Night	24% 9% 25% 25% 15% 1	720
October	1st to 10th	Night	26% 12% 24% 27% 11% 1	720
	11th to 20th	Night	30% 12% 26% 23% 7% 2	720
	21st to end	Night	35% 14% 27% 20% 4	792
November	1st to 10th	Night	31% 16% 26% 21% 5% 1	740
	11th to 20th	Night	28% 19% 27% 16% 9% 1	760
	21st to end	Night	33% 19% 25% 17% 5% 1	760
December	1st to 10th	Night	38% 18% 25% 15% 5%	818
	11th to 20th	Night	32% 19% 27% 16% 5% 1	808
	21st to end	Night	37% 19% 25% 16% 4	836

Page generated at 2024-01-19 09:28:37. Version ac07

Copyright 2024 Attilla Danko