C-Murrinsville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the C-Murrinsville clear sky chart from 2005-11-06 to 2024-02-10.

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	17% 11% 5% 8% 6% 3 5% 4 5% 7% 29%	78323
	Night	17% 12% 5% 8% 6% 3 4 4 5% 6% 30%	80628
Transparency	Day	55% 5% 11% 18% 10% 1	78039
	Night	55% 5% 11% 18% 10% 1	80432
Seeing	Day	24% 15% 28% 19% 10% 4	13597
	Night	23% 13% 27% 24% 11% 1	23358

By Month

Percentage Cloud Cover SE (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% 22% 10% 11% 6% 3 4 3 3 4 16%	2723
	11th to 20th	Day	12% 22% 11% 14% 8% 4 3 3 3 4 16%	2840
	21st to end	Day	25% 19% 10% 13% 9% 3 4 3 3 3 10%	3124
February	1st to 10th	Day	17% 18% 7% 11% 9% 4 4 3 2 4 21%	1701
	11th to 20th	Day	16% 13% 7% 14% 8% 4 4 4 5% 5% 19%	1573
	21st to end	Day	20% 15% 5% 10% 6% 2 5% 5% 4 5% 23%	1459
March	1st to 10th	Day	17% 11% 7% 9% 7% 3 4 5% 5% 7% 27%	1980
	11th to 20th	Day	18% 12% 5% 8% 7% 4 4 4 4 6% 28%	1980
	21st to end	Day	21% 13% 4 7% 7% 3 4 3 4 6% 28%	2178
April	1st to 10th	Day	15% 14% 5% 7% 6% 2 4 4 5% 7% 31%	2088
	11th to 20th	Day	19% 11% 3 7% 5% 3 4 4 5% 6% 33%	2167
	21st to end	Day	22% 10% 4 5% 5% 2 4 4 4 7% 33%	2340
May	1st to 10th	Day	18% 11% 3 8% 5% 4 5% 5% 6% 7% 28%	2340
	11th to 20th	Day	21% 8% 3 6% 6% 4 5% 5% 6% 6% 30%	2305
	21st to end	Day	13% 6% 3 5% 6% 4 6% 6% 7% 8% 37%	2725
June	1st to 10th	Day	15% 7% 3 6% 7% 4 6% 5% 7% 8% 32%	2520
	11th to 20th	Day	14% 7% 4 6% 6% 4 5% 5% 5% 9% 34%	2520
	21st to end	Day	15% 5% 2 5% 5% 4 6% 5% 6% 9% 37%	2520
July	1st to 10th	Day	11% 6% 3 5% 6% 4 6% 6% 6% 8% 40%	2520
	11th to 20th	Day	12% 6% 3 5% 6% 4 5% 6% 6% 9% 38%	2340
	21st to end	Day	12% 6% 3 6% 6% 4 7% 6% 7% 10% 34%	2547
August	1st to 10th	Day	11% 6% 2 5% 6% 4 6% 6% 7% 10% 35%	2327
	11th to 20th	Day	15% 6% 2 7% 6% 4 6% 6% 8% 8% 32%	2303
	21st to end	Day	12% 6% 2 6% 6% 4 6% 6% 7% 8% 36%	2457
September	1st to 10th	Day	16% 8% 3 4 5% 3 4 4 5% 7% 41%	2160
	11th to 20th	Day	13% 7% 3 6% 5% 3 4 5% 5% 9% 41%	2007
	21st to end	Day	18% 7% 3 6% 5% 3 5% 4 5% 7% 36%	1968
October	1st to 10th	Day	17% 7% 3 6% 6% 3 4 5% 6% 8% 36%	1800
	11th to 20th	Day	21% 9% 3 7% 6% 4 5% 4 4 5% 32%	1800
	21st to end	Day	26% 10% 3 7% 5% 3 3 4 5% 6% 27%	1980
November	1st to 10th	Day	11% 9% 4 7% 7% 4 5% 5% 4 7% 38%	1772
	11th to 20th	Day	18% 14% 5% 6% 6% 3 5% 4 5% 5% 29%	1537
	21st to end	Day	19% 18% 6% 8% 7% 2 4 4 4 5% 22%	1520
December	1st to 10th	Day	19% 21% 10% 11% 6% 3 5% 4 4 4 15%	1520
	11th to 20th	Day	17% 19% 7% 13% 6% 3 4 4 4 7% 17%	1910
	21st to end	Day	26% 24% 7% 10% 6% 2 3 3 3 4 12%	2772
January	1st to 10th	Night	17% 22% 11% 13% 6% 3 4 3 3 4 14%	4205
	11th to 20th	Night	16% 18% 9% 15% 7% 4 6% 4 4 4 12%	4120
	21st to end	Night	27% 18% 9% 10% 8% 2 3 3 3 3 14%	4532
February	1st to 10th	Night	18% 14% 6% 11% 9% 5% 4 3 4 4 22%	2464
	11th to 20th	Night	19% 12% 5% 11% 7% 4 6% 5% 4 6% 20%	2273
	21st to end	Night	21% 12% 6% 10% 7% 3 4 5% 5% 5% 23%	1790
March	1st to 10th	Night	16% 13% 5% 7% 7% 4 5% 4 5% 5% 29%	1980
	11th to 20th	Night	19% 11% 5% 6% 6% 3 4 3 4 7% 33%	1980
	21st to end	Night	18% 11% 5% 8% 6% 3 4 4 5% 5% 32%	2178
April	1st to 10th	Night	16% 14% 4 7% 6% 3 3 4 5% 7% 31%	1871
	11th to 20th	Night	18% 9% 3 6% 4 3 5% 4 5% 6% 36%	1758
	21st to end	Night	15% 10% 4 6% 5% 3 5% 4 5% 7% 34%	1620
May	1st to 10th	Night	18% 8% 3 6% 6% 4 5% 5% 6% 6% 33%	1620
	11th to 20th	Night	16% 9% 3 5% 4 3 6% 5% 5% 7% 37%	1584
	21st to end	Night	10% 5% 3 5% 4 3 4 5% 6% 10% 44%	1550
June	1st to 10th	Night	9% 5% 3 5% 5% 4 6% 5% 6% 8% 44%	1440
	11th to 20th	Night	12% 5% 3 6% 4 4 5% 5% 7% 7% 42%	1440
	21st to end	Night	11% 5% 3 6% 5% 3 5% 5% 6% 9% 43%	1440
July	1st to 10th	Night	8% 6% 3 5% 6% 4 5% 5% 5% 8% 46%	1440
	11th to 20th	Night	9% 4 2 4 5% 3 4 5% 6% 9% 48%	1615
	21st to end	Night	10% 6% 2 5% 5% 3 5% 5% 7% 9% 42%	1771
August	1st to 10th	Night	8% 6% 2 5% 5% 3 4 5% 6% 8% 48%	1611
	11th to 20th	Night	11% 6% 3 5% 5% 2 5% 5% 5% 8% 45%	1598
	21st to end	Night	10% 4 2 5% 4 3 4 6% 6% 9% 46%	1880
September	1st to 10th	Night	14% 5% 3 4 6% 3 4 4 6% 6% 47%	1800
	11th to 20th	Night	11% 4 2 4 4 2 3 5% 5% 9% 51%	1950
	21st to end	Night	16% 7% 3 5% 6% 3 5% 4 4 6% 39%	1991
October	1st to 10th	Night	15% 7% 2 5% 5% 3 4 4 5% 7% 42%	2160
	11th to 20th	Night	17% 7% 3 6% 6% 3 4 5% 5% 7% 37%	2160
	21st to end	Night	24% 9% 4 5% 6% 3 4 3 5% 6% 31%	2376
November	1st to 10th	Night	13% 9% 3 6% 5% 3 4 4 5% 7% 41%	2301
	11th to 20th	Night	17% 13% 4 7% 7% 3 4 4 5% 7% 28%	2641
	21st to end	Night	18% 15% 5% 7% 6% 3 5% 4 4 6% 26%	2660
December	1st to 10th	Night	21% 17% 8% 12% 7% 3 4 3 4 5% 16%	2660
	11th to 20th	Night	18% 19% 7% 11% 6% 3 4 4 4 5% 21%	3285
	21st to end	Night	25% 20% 8% 9% 7% 3 4 4 4 4 11%	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	74% 3 8% 10% 5%	2724
	11th to 20th	Day	75% 3 8% 12% 3	2840
	21st to end	Day	81% 2 8% 6% 2	3124
February	1st to 10th	Day	70% 2 9% 12% 7%	1701
	11th to 20th	Day	68% 4 8% 13% 7%	1582
	21st to end	Day	64% 4 10% 14% 7% 1	1459
March	1st to 10th	Day	57% 3 13% 20% 7%	1980
	11th to 20th	Day	58% 5% 9% 17% 9% 2	1980
	21st to end	Day	60% 3 8% 17% 11% 1	2178
April	1st to 10th	Day	53% 4 12% 18% 12% 1	2088
	11th to 20th	Day	53% 4 10% 18% 13% 2	2167
	21st to end	Day	53% 5% 9% 20% 12% 2	2340
May	1st to 10th	Day	54% 5% 11% 19% 9% 2	2340
	11th to 20th	Day	54% 6% 10% 16% 12% 2	2309
	21st to end	Day	43% 7% 16% 22% 11% 2	2725
June	1st to 10th	Day	48% 6% 12% 22% 11% 1	2520
	11th to 20th	Day	47% 6% 14% 20% 13% 1	2520
	21st to end	Day	43% 6% 11% 27% 12% 1	2520
July	1st to 10th	Day	41% 7% 12% 24% 14% 2	2450
	11th to 20th	Day	42% 5% 13% 25% 14% 1	2271
	21st to end	Day	43% 8% 13% 21% 15% 1	2405
August	1st to 10th	Day	41% 7% 14% 29% 8% 1	2314
	11th to 20th	Day	47% 7% 15% 21% 9% 1	2303
	21st to end	Day	44% 7% 11% 22% 14% 2	2457
September	1st to 10th	Day	43% 6% 11% 21% 16% 3	2160
	11th to 20th	Day	40% 6% 13% 25% 15% 1	2007
	21st to end	Day	48% 5% 12% 23% 13%	1968
October	1st to 10th	Day	46% 6% 13% 20% 14% 1	1800
	11th to 20th	Day	55% 5% 11% 21% 9%	1800
	21st to end	Day	58% 4 12% 16% 9% 1	1980
November	1st to 10th	Day	46% 4 13% 19% 16% 2	1772
	11th to 20th	Day	56% 5% 11% 18% 8% 2	1537
	21st to end	Day	65% 4 11% 15% 5% 1	1520
December	1st to 10th	Day	74% 4 10% 9% 3	1520
	11th to 20th	Day	69% 4 9% 14% 3	1906
	21st to end	Day	79% 2 9% 8% 1	2772
January	1st to 10th	Night	75% 3 9% 11% 3	4205
	11th to 20th	Night	76% 4 9% 10% 2	4120
	21st to end	Night	78% 3 6% 10% 3	4532
February	1st to 10th	Night	67% 3 9% 15% 6%	2464
	11th to 20th	Night	65% 4 9% 14% 6%	2275
	21st to end	Night	63% 4 9% 14% 9% 1	1790
March	1st to 10th	Night	56% 4 9% 20% 10%	1980
	11th to 20th	Night	53% 4 12% 20% 10% 1	1980
	21st to end	Night	55% 4 7% 18% 14% 2	2178
April	1st to 10th	Night	53% 5% 10% 18% 13% 1	1871
	11th to 20th	Night	48% 5% 10% 18% 15% 3	1758
	21st to end	Night	48% 6% 10% 22% 11% 3	1620
May	1st to 10th	Night	49% 6% 10% 18% 13% 3	1620
	11th to 20th	Night	45% 6% 11% 20% 15% 2	1585
	21st to end	Night	35% 7% 16% 26% 14% 2	1551
June	1st to 10th	Night	37% 7% 15% 26% 15% 1	1440
	11th to 20th	Night	40% 6% 14% 23% 15% 2	1440
	21st to end	Night	38% 7% 14% 24% 18%	1440
July	1st to 10th	Night	38% 8% 10% 23% 19% 3	1400
	11th to 20th	Night	32% 6% 15% 25% 19% 2	1562
	21st to end	Night	36% 7% 15% 23% 16% 3	1672
August	1st to 10th	Night	33% 7% 16% 27% 16% 1	1600
	11th to 20th	Night	37% 6% 15% 27% 13% 2	1598
	21st to end	Night	33% 8% 14% 26% 16% 3	1880
September	1st to 10th	Night	37% 5% 12% 24% 18% 4	1800
	11th to 20th	Night	30% 6% 13% 28% 22% 1	1950
	21st to end	Night	46% 4 12% 21% 17% 1	1991
October	1st to 10th	Night	41% 5% 14% 23% 15% 2	2160
	11th to 20th	Night	47% 4 13% 23% 12% 1	2160
	21st to end	Night	55% 5% 11% 19% 10% 1	2376
November	1st to 10th	Night	43% 4 12% 24% 14% 3	2301
	11th to 20th	Night	55% 5% 11% 17% 9% 2	2641
	21st to end	Night	59% 4 12% 19% 5% 1	2660
December	1st to 10th	Night	71% 4 11% 9% 4	2660
	11th to 20th	Night	67% 4 11% 14% 3	3288
	21st to end	Night	76% 4 10% 8% 1	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	33% 27% 25% 11% 3 1	240
	11th to 20th	Day	34% 27% 29% 8% 1 1	270
	21st to end	Day	32% 28% 31% 7% 2	297
February	1st to 10th	Day	31% 26% 35% 6% 1	267
	11th to 20th	Day	41% 26% 27% 6%	240
	21st to end	Day	40% 29% 23% 8%	227
March	1st to 10th	Day	32% 23% 31% 11% 2	420
	11th to 20th	Day	33% 17% 35% 11% 4 2	420
	21st to end	Day	33% 21% 27% 14% 5% 1	462
April	1st to 10th	Day	31% 20% 26% 16% 6% 1	420
	11th to 20th	Day	27% 19% 29% 13% 8% 3	412
	21st to end	Day	30% 18% 31% 14% 5% 2	420
May	1st to 10th	Day	29% 17% 30% 16% 6% 2	423
	11th to 20th	Day	26% 12% 32% 19% 9% 2	447
	21st to end	Day	16% 12% 28% 24% 13% 8%	485
June	1st to 10th	Day	16% 14% 31% 26% 11% 3	450
	11th to 20th	Day	20% 15% 23% 27% 13% 3	450
	21st to end	Day	17% 12% 32% 24% 12% 2	450
July	1st to 10th	Day	12% 6% 23% 29% 21% 10%	445
	11th to 20th	Day	14% 6% 28% 27% 18% 7%	444
	21st to end	Day	12% 6% 30% 29% 15% 8%	488
August	1st to 10th	Day	12% 6% 23% 28% 23% 8%	446
	11th to 20th	Day	16% 5% 23% 31% 15% 10%	439
	21st to end	Day	14% 5% 26% 29% 18% 9%	495
September	1st to 10th	Day	20% 6% 21% 26% 19% 7%	450
	11th to 20th	Day	13% 6% 23% 29% 18% 11%	450
	21st to end	Day	23% 10% 26% 23% 15% 4	450
October	1st to 10th	Day	17% 11% 28% 23% 17% 4	450
	11th to 20th	Day	28% 17% 28% 19% 7% 1	450
	21st to end	Day	33% 16% 29% 17% 5%	495
November	1st to 10th	Day	21% 18% 33% 15% 11% 2	370
	11th to 20th	Day	31% 22% 28% 13% 3 2	187
	21st to end	Day	21% 33% 36% 9% 1	180
December	1st to 10th	Day	35% 24% 29% 7% 3 2	180
	11th to 20th	Day	35% 21% 33% 8% 3	180
	21st to end	Day	36% 25% 28% 10% 2	198
January	1st to 10th	Night	30% 22% 33% 13% 2	760
	11th to 20th	Night	32% 21% 30% 14% 3	760
	21st to end	Night	27% 22% 33% 16% 2	836
February	1st to 10th	Night	31% 19% 29% 19% 1	759
	11th to 20th	Night	31% 22% 32% 13% 1	703
	21st to end	Night	32% 21% 29% 15% 2	592
March	1st to 10th	Night	25% 20% 34% 18% 3	720
	11th to 20th	Night	30% 17% 26% 19% 7%	720
	21st to end	Night	26% 15% 35% 19% 4 1	792
April	1st to 10th	Night	26% 16% 31% 20% 6%	720
	11th to 20th	Night	24% 15% 32% 20% 9% 1	694
	21st to end	Night	21% 12% 36% 25% 5% 1	540
May	1st to 10th	Night	23% 10% 24% 31% 11% 1	540
	11th to 20th	Night	19% 10% 29% 32% 10%	523
	21st to end	Night	10% 6% 28% 31% 22% 3	389
June	1st to 10th	Night	9% 4 32% 38% 16% 1	360
	11th to 20th	Night	13% 8% 26% 38% 16%	360
	21st to end	Night	9% 8% 27% 38% 18% 1	360
July	1st to 10th	Night	11% 1 18% 44% 21% 5%	350
	11th to 20th	Night	10% 3 19% 37% 26% 4	518
	21st to end	Night	13% 3 14% 41% 26% 2	591
August	1st to 10th	Night	13% 2 14% 42% 26% 3	537
	11th to 20th	Night	13% 4 13% 38% 28% 4	534
	21st to end	Night	11% 4 21% 33% 26% 5%	692
September	1st to 10th	Night	16% 4 24% 30% 24% 3	720
	11th to 20th	Night	12% 5% 20% 32% 27% 4	720
	21st to end	Night	20% 10% 23% 26% 18% 4	720
October	1st to 10th	Night	19% 7% 24% 28% 20% 2	720
	11th to 20th	Night	21% 12% 33% 25% 8% 1	720
	21st to end	Night	29% 14% 29% 23% 5%	792
November	1st to 10th	Night	19% 13% 29% 27% 11% 1	740
	11th to 20th	Night	28% 17% 27% 19% 6% 1	760
	21st to end	Night	31% 16% 30% 19% 4	760
December	1st to 10th	Night	33% 22% 26% 16% 4	760
	11th to 20th	Night	29% 24% 27% 17% 3	760
	21st to end	Night	31% 20% 30% 17% 2	836

Page generated at 2024-02-07 06:11:53. Version ac07

Copyright 2024 Attilla Danko