North Ram
Clear Sky Chart
History

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

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	9% 10% 3 9% 6% 5% 5% 4 6% 8% 34%	102569
	Night	6% 9% 4 10% 6% 5% 5% 4 6% 8% 36%	96461
Transparency	Day	45% 8% 15% 19% 11% 2	102314
	Night	41% 8% 16% 21% 11% 2	96362
Seeing	Day	21% 16% 29% 23% 10% 2	15778
	Night	14% 14% 31% 27% 12% 1	24185

By Month

Percentage Cloud Cover NW (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 6% 4 15% 8% 7% 6% 5% 7% 9% 31%	2219
	11th to 20th	Day	2 8% 2 11% 6% 5% 5% 7% 6% 9% 38%	2299
	21st to end	Day	1 8% 4 10% 5% 5% 6% 6% 7% 10% 37%	2794
February	1st to 10th	Day	2 9% 6% 10% 9% 8% 6% 5% 7% 8% 30%	1520
	11th to 20th	Day	2 11% 5% 14% 7% 5% 6% 6% 7% 7% 30%	1569
	21st to end	Day	2 8% 4 16% 8% 5% 7% 4 6% 6% 32%	1570
March	1st to 10th	Day	1 6% 3 12% 9% 6% 6% 5% 6% 10% 36%	3138
	11th to 20th	Day	4 10% 3 6% 5% 4 5% 4 7% 10% 42%	3330
	21st to end	Day	3 15% 8% 20% 6% 4 4 3 6% 6% 25%	4039
April	1st to 10th	Day	4 18% 4 11% 7% 7% 6% 5% 7% 8% 23%	2280
	11th to 20th	Day	7% 18% 6% 12% 6% 5% 5% 4 6% 8% 23%	2438
	21st to end	Day	8% 16% 6% 11% 7% 6% 5% 3 6% 6% 26%	2508
May	1st to 10th	Day	14% 20% 4 9% 6% 5% 4 4 5% 7% 24%	4420
	11th to 20th	Day	12% 13% 4 9% 7% 6% 5% 5% 6% 8% 25%	4691
	21st to end	Day	17% 15% 4 11% 6% 6% 6% 4 5% 6% 19%	5161
June	1st to 10th	Day	19% 10% 3 8% 6% 5% 6% 4 6% 7% 25%	2850
	11th to 20th	Day	23% 11% 4 8% 5% 5% 6% 4 6% 8% 20%	3011
	21st to end	Day	13% 8% 3 8% 6% 6% 6% 5% 7% 8% 31%	3040
July	1st to 10th	Day	9% 6% 3 7% 5% 5% 6% 4 5% 6% 44%	4998
	11th to 20th	Day	9% 4 1 5% 4 5% 5% 5% 7% 8% 49%	4740
	21st to end	Day	8% 5% 2 5% 5% 5% 5% 5% 7% 8% 45%	4953
August	1st to 10th	Day	14% 7% 2 5% 4 4 5% 4 7% 8% 40%	4401
	11th to 20th	Day	12% 6% 2 6% 5% 5% 6% 6% 8% 9% 36%	4246
	21st to end	Day	12% 6% 3 6% 4 4 5% 4 6% 7% 42%	4521
September	1st to 10th	Day	14% 9% 2 6% 5% 5% 5% 4 5% 6% 40%	2294
	11th to 20th	Day	13% 11% 2 6% 4 4 5% 3 6% 8% 40%	2151
	21st to end	Day	10% 9% 3 8% 5% 4 5% 3 6% 7% 39%	2090
October	1st to 10th	Day	9% 12% 4 9% 5% 5% 5% 5% 5% 7% 36%	2004
	11th to 20th	Day	8% 11% 3 9% 5% 6% 5% 4 4 8% 39%	1710
	21st to end	Day	5% 12% 5% 10% 6% 5% 5% 4 6% 7% 34%	1881
November	1st to 10th	Day	4 11% 6% 12% 7% 5% 5% 5% 7% 7% 32%	1589
	11th to 20th	Day	3 9% 4 11% 5% 6% 5% 5% 7% 8% 38%	1330
	21st to end	Day	2 10% 2 10% 5% 6% 4 5% 8% 11% 35%	1330
December	1st to 10th	Day	3 11% 4 14% 7% 5% 6% 5% 6% 6% 34%	1330
	11th to 20th	Day	2 8% 4 13% 8% 6% 5% 5% 6% 8% 36%	1682
	21st to end	Day	1 9% 4 10% 6% 5% 5% 4 6% 7% 43%	2442
January	1st to 10th	Night	1 7% 5% 17% 8% 6% 6% 5% 8% 8% 30%	4726
	11th to 20th	Night	1 7% 3 11% 8% 6% 6% 5% 9% 9% 35%	4630
	21st to end	Night	1 8% 5% 11% 7% 6% 6% 4 7% 10% 34%	4862
February	1st to 10th	Night	3 10% 4 11% 9% 7% 6% 4 6% 8% 32%	2660
	11th to 20th	Night	2 10% 5% 13% 7% 7% 5% 6% 7% 8% 31%	2496
	21st to end	Night	7% 5% 13% 8% 6% 6% 5% 7% 7% 35%	1884
March	1st to 10th	Night	1 6% 4 14% 8% 8% 8% 6% 7% 9% 31%	3736
	11th to 20th	Night	4 7% 3 7% 4 4 5% 5% 7% 11% 43%	3648
	21st to end	Night	3 17% 8% 16% 6% 4 4 3 5% 7% 26%	3612
April	1st to 10th	Night	4 12% 5% 10% 7% 6% 6% 5% 6% 9% 31%	1900
	11th to 20th	Night	6% 14% 5% 13% 6% 5% 4 4 6% 7% 30%	1692
	21st to end	Night	6% 16% 5% 9% 5% 5% 4 4 6% 6% 34%	1670
May	1st to 10th	Night	13% 21% 4 9% 5% 4 4 3 4 6% 27%	2540
	11th to 20th	Night	9% 11% 3 9% 6% 6% 6% 5% 7% 8% 30%	2200
	21st to end	Night	14% 11% 3 7% 4 4 6% 5% 8% 8% 29%	2414
June	1st to 10th	Night	19% 8% 3 7% 4 4 4 4 6% 7% 34%	1330
	11th to 20th	Night	19% 9% 3 8% 5% 5% 6% 4 6% 8% 28%	1164
	21st to end	Night	11% 7% 2 6% 5% 4 4 4 6% 9% 42%	1140
July	1st to 10th	Night	10% 6% 3 8% 5% 4 4 3 5% 8% 44%	1959
	11th to 20th	Night	7% 4 1 4 3 3 3 3 7% 9% 57%	2220
	21st to end	Night	6% 4 2 5% 4 4 4 4 6% 7% 52%	2597
August	1st to 10th	Night	14% 7% 2 5% 3 3 4 3 5% 9% 45%	2529
	11th to 20th	Night	13% 7% 2 5% 3 4 5% 4 7% 11% 40%	2583
	21st to end	Night	13% 7% 2 6% 4 4 3 3 5% 8% 45%	3146
September	1st to 10th	Night	11% 7% 3 5% 4 3 4 4 5% 8% 46%	1884
	11th to 20th	Night	14% 10% 3 6% 3 3 3 4 5% 8% 41%	2028
	21st to end	Night	8% 9% 3 6% 3 3 4 4 7% 7% 44%	2090
October	1st to 10th	Night	8% 10% 4 7% 5% 5% 4 4 5% 8% 42%	2172
	11th to 20th	Night	7% 9% 3 9% 5% 4 5% 3 6% 8% 40%	2470
	21st to end	Night	5% 10% 4 10% 6% 5% 5% 5% 7% 7% 36%	2717
November	1st to 10th	Night	3 13% 6% 11% 6% 5% 4 4 6% 7% 35%	2488
	11th to 20th	Night	2 10% 4 9% 6% 6% 6% 5% 6% 10% 36%	2850
	21st to end	Night	2 9% 4 12% 8% 5% 6% 5% 6% 9% 34%	2850
December	1st to 10th	Night	3 9% 5% 12% 7% 5% 6% 5% 6% 7% 35%	2850
	11th to 20th	Night	1 8% 5% 12% 9% 7% 6% 5% 8% 8% 31%	3510
	21st to end	Night	1 8% 5% 12% 6% 5% 6% 4 6% 8% 39%	5214

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	44% 7% 14% 20% 10% 5%	2219
	11th to 20th	Day	37% 8% 15% 15% 19% 6%	2320
	21st to end	Day	35% 11% 18% 27% 9% 1	2794
February	1st to 10th	Day	46% 8% 14% 16% 12% 3	1520
	11th to 20th	Day	47% 11% 12% 17% 12% 2	1577
	21st to end	Day	50% 7% 14% 14% 14% 2	1570
March	1st to 10th	Day	38% 6% 21% 17% 17% 2	3138
	11th to 20th	Day	34% 8% 21% 19% 17% 1	3331
	21st to end	Day	56% 9% 12% 14% 5% 3	4039
April	1st to 10th	Day	56% 8% 16% 14% 6%	2280
	11th to 20th	Day	59% 8% 12% 16% 6% 1	2438
	21st to end	Day	58% 8% 12% 14% 6% 1	2508
May	1st to 10th	Day	58% 8% 11% 18% 4	4420
	11th to 20th	Day	51% 8% 15% 17% 8%	4695
	21st to end	Day	59% 8% 16% 10% 7%	5162
June	1st to 10th	Day	56% 9% 12% 14% 7% 1	2850
	11th to 20th	Day	60% 9% 11% 12% 7% 1	3011
	21st to end	Day	47% 10% 15% 16% 9% 2	3040
July	1st to 10th	Day	38% 7% 10% 18% 20% 7%	4920
	11th to 20th	Day	30% 9% 12% 26% 18% 4	4659
	21st to end	Day	34% 8% 14% 24% 18% 2	4796
August	1st to 10th	Day	40% 9% 13% 29% 9%	4384
	11th to 20th	Day	40% 10% 18% 22% 9% 1	4288
	21st to end	Day	38% 8% 19% 27% 7% 1	4520
September	1st to 10th	Day	43% 8% 14% 21% 11% 2	2294
	11th to 20th	Day	42% 7% 15% 24% 11% 2	2151
	21st to end	Day	42% 7% 18% 18% 12% 3	2090
October	1st to 10th	Day	45% 8% 13% 24% 9% 1	2004
	11th to 20th	Day	42% 8% 17% 22% 11% 1	1710
	21st to end	Day	46% 9% 13% 21% 10% 1	1881
November	1st to 10th	Day	47% 9% 15% 18% 9% 2	1589
	11th to 20th	Day	39% 10% 19% 20% 12% 1	1330
	21st to end	Day	38% 10% 20% 19% 9% 4	1330
December	1st to 10th	Day	47% 8% 14% 16% 12% 2	1330
	11th to 20th	Day	42% 9% 16% 19% 12% 2	1684
	21st to end	Day	38% 5% 13% 21% 16% 7%	2442
January	1st to 10th	Night	46% 8% 13% 18% 11% 3	4726
	11th to 20th	Night	40% 8% 14% 13% 16% 9%	4671
	21st to end	Night	40% 10% 20% 19% 10% 1	4862
February	1st to 10th	Night	47% 9% 14% 16% 12% 3	2660
	11th to 20th	Night	44% 9% 18% 15% 12% 2	2498
	21st to end	Night	45% 6% 13% 21% 14% 2	1884
March	1st to 10th	Night	41% 7% 21% 15% 14% 2	3736
	11th to 20th	Night	32% 7% 21% 21% 18% 1	3648
	21st to end	Night	54% 7% 14% 15% 8% 1	3612
April	1st to 10th	Night	46% 8% 17% 17% 11% 1	1900
	11th to 20th	Night	52% 6% 14% 17% 10% 1	1692
	21st to end	Night	47% 11% 13% 21% 7% 1	1670
May	1st to 10th	Night	58% 6% 13% 17% 5%	2540
	11th to 20th	Night	44% 7% 16% 25% 9%	2200
	21st to end	Night	44% 8% 18% 20% 10%	2414
June	1st to 10th	Night	47% 9% 14% 20% 9% 1	1330
	11th to 20th	Night	53% 10% 15% 15% 7% 1	1164
	21st to end	Night	36% 9% 19% 25% 9% 2	1140
July	1st to 10th	Night	36% 7% 12% 24% 14% 7%	1928
	11th to 20th	Night	22% 7% 20% 32% 12% 7%	2178
	21st to end	Night	29% 6% 16% 32% 16% 1	2515
August	1st to 10th	Night	36% 8% 14% 37% 5%	2521
	11th to 20th	Night	35% 9% 22% 26% 7%	2607
	21st to end	Night	37% 6% 18% 31% 7% 1	3146
September	1st to 10th	Night	35% 8% 17% 26% 10% 3	1884
	11th to 20th	Night	41% 6% 16% 25% 10% 3	2028
	21st to end	Night	36% 7% 18% 25% 13% 1	2090
October	1st to 10th	Night	40% 8% 15% 25% 11% 1	2172
	11th to 20th	Night	40% 8% 19% 22% 11% 1	2470
	21st to end	Night	43% 10% 14% 22% 10%	2717
November	1st to 10th	Night	45% 9% 13% 19% 11% 3	2488
	11th to 20th	Night	39% 9% 17% 21% 11% 2	2850
	21st to end	Night	43% 11% 15% 19% 9% 4	2850
December	1st to 10th	Night	44% 9% 13% 19% 13% 3	2850
	11th to 20th	Night	45% 13% 15% 18% 8% 1	3507
	21st to end	Night	40% 7% 14% 21% 12% 6%	5214

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% 17% 27% 27% 14% 4	180
	11th to 20th	Day	14% 11% 35% 27% 9% 3	180
	21st to end	Day	16% 16% 38% 21% 7% 2	198
February	1st to 10th	Day	22% 15% 37% 17% 7% 2	180
	11th to 20th	Day	13% 19% 35% 23% 10%	231
	21st to end	Day	14% 22% 30% 23% 8% 2	382
March	1st to 10th	Day	17% 23% 33% 17% 7% 2	460
	11th to 20th	Day	17% 19% 35% 20% 7% 2	460
	21st to end	Day	22% 23% 28% 18% 7% 2	506
April	1st to 10th	Day	25% 21% 28% 19% 6% 1	460
	11th to 20th	Day	20% 21% 28% 21% 8% 2	452
	21st to end	Day	24% 18% 27% 20% 9% 2	460
May	1st to 10th	Day	28% 17% 24% 21% 9% 1	463
	11th to 20th	Day	19% 10% 30% 25% 13% 2	672
	21st to end	Day	28% 8% 24% 25% 12% 3	734
June	1st to 10th	Day	25% 14% 30% 22% 8% 2	680
	11th to 20th	Day	29% 14% 24% 21% 11% 2	841
	21st to end	Day	18% 12% 24% 27% 16% 3	870
July	1st to 10th	Day	17% 11% 26% 30% 14% 2	821
	11th to 20th	Day	18% 10% 27% 25% 18% 2	668
	21st to end	Day	15% 12% 28% 27% 15% 3	629
August	1st to 10th	Day	16% 14% 28% 27% 11% 4	487
	11th to 20th	Day	16% 16% 30% 25% 10% 3	477
	21st to end	Day	19% 15% 29% 24% 10% 3	539
September	1st to 10th	Day	25% 18% 26% 20% 9% 1	490
	11th to 20th	Day	24% 14% 27% 25% 7% 3	490
	21st to end	Day	27% 19% 27% 18% 7% 2	490
October	1st to 10th	Day	23% 16% 29% 18% 10% 4	466
	11th to 20th	Day	23% 14% 30% 22% 9% 2	300
	21st to end	Day	22% 17% 32% 21% 8% 1	330
November	1st to 10th	Day	22% 22% 31% 17% 6% 2	264
	11th to 20th	Day	22% 18% 36% 16% 6% 1	180
	21st to end	Day	18% 21% 30% 20% 7% 4	180
December	1st to 10th	Day	14% 18% 32% 19% 11% 5%	180
	11th to 20th	Day	14% 21% 36% 22% 6% 1	180
	21st to end	Day	12% 11% 34% 30% 11% 2	198
January	1st to 10th	Night	13% 18% 39% 24% 6%	950
	11th to 20th	Night	11% 17% 43% 21% 6% 1	907
	21st to end	Night	15% 18% 40% 19% 8% 1	836
February	1st to 10th	Night	13% 17% 32% 26% 11% 1	760
	11th to 20th	Night	11% 15% 37% 29% 7% 1	744
	21st to end	Night	7% 13% 37% 27% 15% 2	628
March	1st to 10th	Night	8% 17% 36% 28% 10% 2	760
	11th to 20th	Night	10% 15% 37% 28% 9% 1	760
	21st to end	Night	13% 13% 31% 29% 11% 3	836
April	1st to 10th	Night	14% 16% 27% 29% 14% 1	760
	11th to 20th	Night	15% 15% 33% 27% 10%	564
	21st to end	Night	20% 15% 28% 27% 10% 1	530
May	1st to 10th	Night	22% 9% 23% 31% 14% 1	380
	11th to 20th	Night	16% 7% 24% 36% 15% 2	374
	21st to end	Night	26% 5% 19% 27% 22% 1	411
June	1st to 10th	Night	25% 9% 23% 26% 15% 2	380
	11th to 20th	Night	22% 9% 21% 30% 17% 2	380
	21st to end	Night	16% 10% 18% 31% 22% 3	380
July	1st to 10th	Night	17% 4 19% 37% 23% 1	370
	11th to 20th	Night	15% 8% 21% 36% 21%	368
	21st to end	Night	12% 6% 14% 41% 25% 3	416
August	1st to 10th	Night	19% 3 12% 33% 29% 4	378
	11th to 20th	Night	14% 4 17% 38% 25% 2	423
	21st to end	Night	17% 9% 19% 35% 19% 1	627
September	1st to 10th	Night	15% 9% 23% 35% 16% 2	744
	11th to 20th	Night	21% 7% 20% 32% 18% 2	760
	21st to end	Night	17% 15% 29% 26% 12% 1	760
October	1st to 10th	Night	17% 11% 26% 33% 11% 2	760
	11th to 20th	Night	15% 14% 33% 28% 8% 1	760
	21st to end	Night	16% 15% 38% 23% 7% 1	836
November	1st to 10th	Night	15% 18% 35% 23% 8% 1	798
	11th to 20th	Night	13% 24% 38% 20% 4 1	950
	21st to end	Night	13% 22% 36% 21% 8% 1	950
December	1st to 10th	Night	12% 18% 39% 22% 8% 1	950
	11th to 20th	Night	9% 20% 38% 25% 8% 1	950
	21st to end	Night	8% 16% 41% 25% 9% 1	1045

Page generated at 2024-10-29 23:22:57. Version ac07

Copyright © 2024 Attilla Danko.