TAMUK Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the TAMUK Observatory clear sky chart from 2005-11-06 to 2024-11-03.

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% 5% 2 6% 4 4 5% 4 6% 8% 44%	100909
	Night	12% 6% 2 5% 3 3 4 3 5% 7% 49%	98192
Transparency	Day	35% 8% 14% 23% 14% 6%	100720
	Night	34% 7% 16% 22% 14% 7%	98052
Seeing	Day	11% 5% 22% 33% 22% 7%	14486
	Night	14% 4 23% 37% 21% 2	24430

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	15% 7% 2 6% 4 4 4 3 5% 6% 45%	2847
	11th to 20th	Day	14% 5% 2 5% 4 3 4 3 4 7% 50%	2859
	21st to end	Day	22% 7% 3 6% 4 4 3 4 6% 6% 36%	3487
February	1st to 10th	Day	20% 7% 2 6% 4 5% 3 3 5% 5% 39%	1900
	11th to 20th	Day	18% 6% 3 6% 3 3 3 2 5% 6% 45%	1849
	21st to end	Day	16% 8% 2 6% 4 3 3 3 5% 5% 45%	1594
March	1st to 10th	Day	19% 7% 3 8% 5% 4 5% 4 6% 8% 32%	3436
	11th to 20th	Day	26% 9% 3 9% 5% 4 4 3 4 6% 28%	3480
	21st to end	Day	9% 5% 2 4 4 4 4 4 5% 7% 53%	3814
April	1st to 10th	Day	11% 6% 3 6% 4 4 4 4 6% 7% 44%	2090
	11th to 20th	Day	14% 7% 3 7% 5% 4 4 3 6% 7% 41%	2066
	21st to end	Day	11% 7% 2 6% 5% 4 5% 4 7% 7% 43%	2247
May	1st to 10th	Day	12% 6% 2 7% 5% 5% 5% 5% 7% 10% 36%	4082
	11th to 20th	Day	8% 6% 3 7% 5% 5% 6% 5% 6% 8% 42%	4082
	21st to end	Day	6% 4 2 4 3 4 5% 5% 7% 9% 52%	4477
June	1st to 10th	Day	4 3 1 4 4 5% 5% 5% 7% 10% 52%	2470
	11th to 20th	Day	4 3 1 6% 5% 5% 5% 4 7% 11% 48%	2470
	21st to end	Day	7% 5% 1 6% 5% 5% 7% 6% 8% 11% 40%	2470
July	1st to 10th	Day	6% 5% 2 6% 5% 5% 6% 5% 7% 10% 44%	4120
	11th to 20th	Day	5% 5% 3 9% 6% 7% 7% 6% 9% 10% 34%	4120
	21st to end	Day	9% 6% 2 7% 5% 5% 6% 5% 7% 9% 39%	4465
August	1st to 10th	Day	1 1 1 2 2 3 3 3 5% 9% 70%	3925
	11th to 20th	Day	3 2 1 3 4 4 5% 5% 9% 13% 50%	3726
	21st to end	Day	4 3 2 7% 5% 6% 7% 5% 9% 12% 40%	3895
September	1st to 10th	Day	9% 6% 3 9% 7% 6% 6% 5% 7% 9% 34%	2090
	11th to 20th	Day	10% 6% 3 9% 5% 6% 6% 5% 6% 10% 35%	2090
	21st to end	Day	7% 5% 3 6% 4 5% 5% 4 8% 9% 44%	2090
October	1st to 10th	Day	6% 4 2 5% 5% 5% 6% 5% 6% 8% 49%	2090
	11th to 20th	Day	10% 5% 1 5% 5% 4 4 4 5% 7% 48%	1981
	21st to end	Day	8% 4 2 5% 2 4 3 3 5% 6% 57%	2090
November	1st to 10th	Day	10% 4 3 7% 5% 4 5% 5% 6% 7% 44%	1878
	11th to 20th	Day	14% 8% 2 6% 4 4 4 3 5% 6% 44%	1900
	21st to end	Day	17% 7% 3 4 4 4 5% 4 4 7% 42%	1723
December	1st to 10th	Day	19% 7% 2 5% 4 3 4 3 5% 7% 42%	1710
	11th to 20th	Day	15% 8% 2 6% 5% 4 4 4 5% 6% 40%	2161
	21st to end	Day	16% 6% 2 6% 4 4 4 4 5% 7% 43%	3135
January	1st to 10th	Night	19% 5% 2 5% 3 3 3 3 4 5% 46%	4108
	11th to 20th	Night	15% 5% 2 4 2 2 3 3 4 7% 53%	4120
	21st to end	Night	23% 7% 2 7% 3 3 4 3 6% 6% 35%	4198
February	1st to 10th	Night	18% 7% 2 5% 4 4 4 4 5% 5% 43%	2280
	11th to 20th	Night	19% 7% 2 5% 3 4 3 4 4 5% 45%	2218
	21st to end	Night	17% 7% 2 5% 4 3 3 3 4 5% 47%	1860
March	1st to 10th	Night	23% 8% 2 6% 3 3 4 3 5% 7% 35%	3419
	11th to 20th	Night	25% 11% 3 9% 5% 4 3 4 4 5% 26%	3480
	21st to end	Night	13% 4 2 4 3 2 2 2 4 6% 58%	3817
April	1st to 10th	Night	13% 6% 2 5% 5% 4 5% 4 7% 10% 39%	2090
	11th to 20th	Night	18% 7% 2 5% 4 3 4 3 5% 6% 42%	2063
	21st to end	Night	16% 8% 2 6% 5% 4 4 3 5% 7% 39%	1927
May	1st to 10th	Night	22% 7% 3 5% 4 3 4 3 6% 8% 36%	2823
	11th to 20th	Night	15% 8% 2 7% 4 5% 4 3 5% 7% 39%	2823
	21st to end	Night	9% 6% 3 7% 4 4 3 4 6% 10% 45%	3090
June	1st to 10th	Night	3 3 1 4 4 4 4 3 7% 10% 58%	1710
	11th to 20th	Night	4 3 2 4 4 3 4 3 7% 10% 57%	1710
	21st to end	Night	4 4 1 4 3 5% 3 4 8% 10% 52%	1710
July	1st to 10th	Night	4 3 1 3 4 3 4 4 7% 12% 55%	2850
	11th to 20th	Night	4 4 2 6% 5% 5% 7% 5% 8% 11% 43%	2850
	21st to end	Night	7% 4 2 5% 4 3 4 3 6% 11% 51%	3098
August	1st to 10th	Night	1 1 1 1 2 3 6% 83%	3009
	11th to 20th	Night	2 2 1 3 3 3 4 4 7% 12% 60%	3113
	21st to end	Night	2 2 1 3 2 3 3 3 5% 12% 63%	3761
September	1st to 10th	Night	6% 5% 2 7% 5% 4 4 4 7% 9% 47%	2090
	11th to 20th	Night	8% 6% 3 6% 4 4 5% 4 5% 9% 46%	2090
	21st to end	Night	6% 4 2 5% 3 4 3 3 5% 8% 57%	2090
October	1st to 10th	Night	4 3 1 4 2 3 3 3 5% 7% 65%	2090
	11th to 20th	Night	10% 5% 2 3 3 2 3 3 5% 6% 58%	2180
	21st to end	Night	9% 4 1 5% 3 2 3 2 3 4 64%	2508
November	1st to 10th	Night	11% 4 2 4 3 3 3 3 4 5% 56%	2245
	11th to 20th	Night	14% 5% 2 7% 3 3 3 3 3 4 53%	2280
	21st to end	Night	16% 7% 2 5% 3 3 3 3 5% 5% 46%	2454
December	1st to 10th	Night	17% 7% 2 5% 4 3 3 2 4 6% 46%	2470
	11th to 20th	Night	18% 8% 3 5% 4 3 4 3 4 5% 42%	3036
	21st to end	Night	14% 8% 3 6% 4 3 4 3 5% 6% 44%	4532

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	37% 7% 7% 14% 20% 14%	2848
	11th to 20th	Day	34% 5% 7% 23% 18% 13%	2859
	21st to end	Day	47% 5% 7% 15% 17% 9%	3487
February	1st to 10th	Day	47% 5% 8% 10% 17% 13%	1900
	11th to 20th	Day	41% 3 10% 18% 16% 11%	1859
	21st to end	Day	41% 5% 7% 18% 19% 9%	1594
March	1st to 10th	Day	48% 7% 12% 17% 11% 6%	3436
	11th to 20th	Day	55% 8% 8% 11% 12% 6%	3480
	21st to end	Day	30% 5% 11% 24% 16% 14%	3814
April	1st to 10th	Day	37% 6% 13% 18% 16% 10%	2090
	11th to 20th	Day	39% 9% 10% 18% 14% 10%	2066
	21st to end	Day	35% 9% 12% 20% 14% 10%	2247
May	1st to 10th	Day	38% 11% 17% 19% 10% 5%	4120
	11th to 20th	Day	35% 11% 13% 18% 16% 8%	4086
	21st to end	Day	24% 8% 12% 41% 14% 1	4489
June	1st to 10th	Day	22% 9% 16% 32% 18% 3	2470
	11th to 20th	Day	25% 10% 13% 30% 19% 4	2470
	21st to end	Day	30% 13% 19% 28% 9% 1	2470
July	1st to 10th	Day	31% 11% 22% 31% 5%	4056
	11th to 20th	Day	41% 10% 24% 18% 7%	4051
	21st to end	Day	37% 10% 24% 25% 4	4325
August	1st to 10th	Day	10% 6% 20% 45% 18%	3911
	11th to 20th	Day	20% 10% 34% 32% 4	3762
	21st to end	Day	30% 12% 22% 27% 9% 1	3894
September	1st to 10th	Day	43% 11% 15% 16% 13% 2	2090
	11th to 20th	Day	41% 11% 13% 20% 12% 3	2090
	21st to end	Day	31% 10% 14% 23% 14% 9%	2090
October	1st to 10th	Day	29% 8% 11% 20% 24% 7%	2090
	11th to 20th	Day	33% 8% 9% 20% 17% 13%	1981
	21st to end	Day	26% 6% 7% 19% 27% 15%	2090
November	1st to 10th	Day	35% 7% 11% 20% 18% 8%	1878
	11th to 20th	Day	42% 5% 12% 16% 15% 11%	1900
	21st to end	Day	42% 6% 11% 15% 18% 10%	1723
December	1st to 10th	Day	41% 5% 10% 19% 18% 7%	1710
	11th to 20th	Day	42% 7% 8% 13% 17% 13%	2159
	21st to end	Day	40% 6% 7% 18% 20% 9%	3135
January	1st to 10th	Night	39% 5% 8% 12% 17% 19%	4108
	11th to 20th	Night	32% 4 7% 21% 19% 16%	4120
	21st to end	Night	49% 5% 7% 13% 18% 8%	4198
February	1st to 10th	Night	42% 6% 10% 13% 14% 15%	2280
	11th to 20th	Night	42% 6% 10% 15% 17% 11%	2218
	21st to end	Night	41% 5% 9% 20% 16% 9%	1860
March	1st to 10th	Night	48% 6% 13% 16% 12% 5%	3419
	11th to 20th	Night	60% 6% 10% 9% 9% 6%	3480
	21st to end	Night	27% 5% 14% 21% 22% 10%	3817
April	1st to 10th	Night	40% 7% 14% 18% 12% 8%	2090
	11th to 20th	Night	42% 6% 12% 16% 13% 11%	2063
	21st to end	Night	43% 8% 10% 16% 14% 9%	1927
May	1st to 10th	Night	45% 7% 15% 19% 9% 6%	2850
	11th to 20th	Night	42% 9% 12% 20% 13% 3	2824
	21st to end	Night	32% 9% 17% 33% 7%	3099
June	1st to 10th	Night	21% 6% 20% 34% 17% 2	1710
	11th to 20th	Night	22% 7% 13% 36% 19% 2	1710
	21st to end	Night	25% 9% 25% 31% 10% 1	1710
July	1st to 10th	Night	22% 8% 31% 34% 4	2805
	11th to 20th	Night	31% 12% 30% 20% 6%	2796
	21st to end	Night	28% 9% 33% 26% 4	2999
August	1st to 10th	Night	5% 5% 24% 49% 17%	2999
	11th to 20th	Night	18% 8% 40% 31% 4	3143
	21st to end	Night	16% 10% 32% 32% 9% 1	3761
September	1st to 10th	Night	32% 10% 25% 18% 11% 3	2090
	11th to 20th	Night	34% 9% 18% 27% 11% 2	2090
	21st to end	Night	26% 7% 16% 28% 17% 7%	2090
October	1st to 10th	Night	19% 7% 16% 28% 21% 9%	2090
	11th to 20th	Night	26% 7% 12% 24% 18% 13%	2180
	21st to end	Night	24% 5% 7% 21% 26% 17%	2508
November	1st to 10th	Night	28% 8% 12% 21% 23% 8%	2245
	11th to 20th	Night	36% 5% 12% 19% 18% 10%	2280
	21st to end	Night	39% 5% 11% 21% 14% 10%	2454
December	1st to 10th	Night	39% 5% 11% 20% 16% 9%	2470
	11th to 20th	Night	42% 6% 7% 17% 13% 14%	3037
	21st to end	Night	40% 7% 10% 13% 17% 13%	4532

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	21% 8% 31% 28% 9% 3	270
	11th to 20th	Day	17% 7% 35% 29% 10% 2	270
	21st to end	Day	23% 11% 33% 23% 10% 1	297
February	1st to 10th	Day	25% 10% 28% 23% 15%	270
	11th to 20th	Day	23% 9% 33% 27% 8%	270
	21st to end	Day	18% 12% 43% 21% 6%	225
March	1st to 10th	Day	20% 11% 34% 29% 6%	270
	11th to 20th	Day	23% 10% 42% 20% 5%	270
	21st to end	Day	13% 10% 42% 30% 4	297
April	1st to 10th	Day	18% 10% 37% 28% 7% 1	270
	11th to 20th	Day	12% 14% 39% 25% 8% 1	264
	21st to end	Day	13% 11% 39% 30% 7%	427
May	1st to 10th	Day	11% 9% 44% 26% 9%	653
	11th to 20th	Day	12% 5% 39% 32% 11% 2	675
	21st to end	Day	8% 4 36% 36% 15% 1	734
June	1st to 10th	Day	4 1 19% 42% 29% 5%	680
	11th to 20th	Day	5% 1 17% 46% 26% 4	680
	21st to end	Day	6% 2 13% 40% 29% 10%	680
July	1st to 10th	Day	6% 1 10% 41% 34% 9%	671
	11th to 20th	Day	4 1 6% 40% 38% 11%	668
	21st to end	Day	4 1 7% 41% 36% 11%	739
August	1st to 10th	Day	1 1 6% 44% 33% 15%	575
	11th to 20th	Day	3 1 7% 44% 32% 14%	477
	21st to end	Day	4 2 4 31% 31% 27%	371
September	1st to 10th	Day	11% 1 8% 26% 38% 16%	300
	11th to 20th	Day	7% 1 6% 21% 43% 22%	300
	21st to end	Day	7% 1 8% 20% 42% 22%	300
October	1st to 10th	Day	8% 2 5% 31% 39% 16%	300
	11th to 20th	Day	11% 1 13% 32% 28% 15%	300
	21st to end	Day	11% 5% 24% 32% 22% 7%	330
November	1st to 10th	Day	14% 3 16% 33% 29% 5%	276
	11th to 20th	Day	22% 4 18% 25% 25% 6%	270
	21st to end	Day	25% 6% 27% 26% 12% 4	270
December	1st to 10th	Day	22% 3 19% 32% 19% 6%	270
	11th to 20th	Day	18% 13% 26% 28% 14% 2	270
	21st to end	Day	19% 12% 25% 28% 12% 4	297
January	1st to 10th	Night	21% 6% 26% 35% 11%	950
	11th to 20th	Night	19% 7% 29% 36% 8% 1	950
	21st to end	Night	22% 8% 26% 35% 9%	841
February	1st to 10th	Night	22% 7% 33% 32% 6%	760
	11th to 20th	Night	23% 8% 31% 31% 6%	744
	21st to end	Night	22% 9% 39% 25% 5%	604
March	1st to 10th	Night	21% 9% 33% 29% 6% 1	570
	11th to 20th	Night	18% 9% 37% 31% 5%	570
	21st to end	Night	13% 8% 41% 33% 4	627
April	1st to 10th	Night	13% 8% 41% 32% 6%	570
	11th to 20th	Night	20% 8% 34% 31% 7%	563
	21st to end	Night	18% 8% 40% 28% 6%	570
May	1st to 10th	Night	14% 6% 41% 33% 6%	570
	11th to 20th	Night	13% 4 33% 40% 10%	561
	21st to end	Night	8% 4 29% 45% 14%	617
June	1st to 10th	Night	4 1 18% 52% 25% 1	570
	11th to 20th	Night	5% 1 17% 57% 20% 1	570
	21st to end	Night	5% 2 14% 44% 33% 2	570
July	1st to 10th	Night	5% 1 9% 48% 33% 4	555
	11th to 20th	Night	1 1 5% 47% 43% 3	552
	21st to end	Night	3 1 6% 47% 39% 4	624
August	1st to 10th	Night	4 44% 47% 4	567
	11th to 20th	Night	4 4 43% 45% 4	564
	21st to end	Night	5% 5% 29% 53% 8%	627
September	1st to 10th	Night	6% 1 5% 30% 50% 7%	570
	11th to 20th	Night	11% 1 5% 24% 49% 10%	570
	21st to end	Night	8% 1 8% 29% 48% 7%	570
October	1st to 10th	Night	4 1 5% 36% 49% 5%	570
	11th to 20th	Night	12% 2 14% 43% 26% 3	660
	21st to end	Night	9% 3 23% 41% 22% 2	836
November	1st to 10th	Night	11% 3 18% 42% 25% 2	749
	11th to 20th	Night	17% 2 24% 37% 19% 2	760
	21st to end	Night	19% 6% 24% 34% 17% 1	934
December	1st to 10th	Night	18% 5% 23% 36% 16% 1	950
	11th to 20th	Night	24% 7% 25% 34% 10%	950
	21st to end	Night	19% 6% 29% 35% 11% 1	1045

Page generated at 2024-10-31 02:39:26. Version ac07

Copyright © 2024 Attilla Danko.