New Mexico Skies
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the New Mexico Skies clear sky chart from 2005-11-05 to 2008-12-24.

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	6% 5% 5% 5% 8% 54%	12482
	Night	5% 5% 9% 61%	12545
Cloud Cover	Day	5% 5% 5% 5% 7% 54%	12475
	Night	5% 8% 61%	12553
Transparency	Day	12% 22% 29% 17%	10289
	Night	13% 22% 31% 19%	10734
Seeing	Day	16% 26% 32% 16%	625
	Night	18% 27% 28% 17%	3866

By Month

Percentage Cloud Cover
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month		Occurrence of each Forecast	Data Points
January	Day	6% 6% 9% 57%	835
	Night	5% 6% 9% 56%	1203
February	Day	8% 68%	806
	Night	5% 9% 72%	973
March	Day	7% 58%	1017
	Night	6% 8% 60%	1021
April	Day	5% 6% 69%	1077
	Night	5% 7% 69%	899
May	Day	5% 7% 5% 7% 55%	1141
	Night	5% 5% 5% 6% 62%	903
June	Day	7% 7% 8% 10% 47%	1257
	Night	11% 7% 5% 9% 49%	721
July	Day	17% 5% 6% 10% 8% 9% 10% 19%	1203
	Night	11% 8% 6% 10% 16% 28%	837
August	Day	15% 7% 10% 8% 6% 8% 26%	1108
	Night	9% 5% 5% 6% 6% 13% 39%	929
September	Day	9% 5% 5% 9% 49%	1043
	Night	7% 5% 9% 57%	931
October	Day	6% 72%	925
	Night	6% 75%	1107
November	Day	6% 74%	1076
	Night	6% 70%	1454
December	Day	5% 8% 69%	994
	Night	7% 71%	1567

Percentage Cloud Cover
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month		Occurrence of each Forecast	Data Points
January	Day	6% 6% 8% 58%	834
	Night	7% 7% 57%	1206
February	Day	7% 69%	806
	Night	5% 8% 73%	973
March	Day	5% 8% 58%	1018
	Night	5% 8% 60%	1023
April	Day	5% 5% 69%	1077
	Night	5% 5% 6% 69%	899
May	Day	5% 6% 5% 5% 8% 55%	1140
	Night	5% 5% 5% 6% 62%	903
June	Day	7% 7% 8% 9% 47%	1257
	Night	11% 8% 8% 49%	721
July	Day	17% 6% 5% 10% 8% 8% 10% 19%	1203
	Night	10% 8% 6% 10% 15% 28%	838
August	Day	14% 6% 5% 7% 5% 8% 8% 6% 7% 26%	1102
	Night	9% 5% 5% 5% 7% 14% 38%	930
September	Day	8% 6% 8% 49%	1045
	Night	7% 5% 5% 9% 56%	931
October	Day	5% 73%	926
	Night	5% 75%	1107
November	Day	5% 73%	1073
	Night	6% 70%	1454
December	Day	5% 7% 68%	994
	Night	7% 71%	1568

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	14% 25% 29% 18%	708
	Night	14% 22% 33% 15%	1007
February	Day	8% 23% 45% 16%	713
	Night	10% 19% 44% 19%	918
March	Day	14% 23% 33% 17%	824
	Night	13% 20% 36% 22%	830
April	Day	8% 12% 34% 39%	923
	Night	8% 16% 31% 37%	787
May	Day	6% 11% 17% 29% 26%	908
	Night	11% 20% 35% 24%	729
June	Day	7% 18% 16% 21% 27%	975
	Night	9% 14% 16% 19% 30%	560
July	Day	9% 24% 17% 9%	657
	Night	13% 33% 21% 11%	470
August	Day	7% 20% 25% 8%	838
	Night	8% 29% 27% 10%	746
September	Day	11% 21% 27% 10%	943
	Night	5% 16% 24% 24% 11%	861
October	Day	7% 19% 36% 27%	859
	Night	8% 14% 35% 32%	1024
November	Day	8% 29% 37% 13%	1031
	Night	6% 25% 36% 19%	1370
December	Day	11% 32% 38% 9%	910
	Night	11% 29% 33% 17%	1432

Seeing (when cloud cover <= 80%)
Color Meanings: Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month		Occurrence of each Forecast	Data Points
January	Night	32% 32% 21% 5%	348
February	Night	33% 31% 19% 7%	289
March	Day	34% 52% 7%	63
	Night	23% 38% 26% 7%	316
April	Day	44% 37% 8%	72
	Night	27% 37% 25% 5%	251
May	Day	25% 39% 20% 6%	107
	Night	13% 36% 28% 13%	271
June	Day	9% 18% 42% 23%	169
	Night	6% 18% 44% 25%	250
July	Day	16% 47% 26%	72
	Night	32% 49% 6%	230
August	Day	6% 47% 30% 6%	88
	Night	23% 50% 15%	256
September	Day	27% 37% 16%	54
	Night	5% 11% 38% 34%	252
October	Night	10% 25% 33% 19% 8%	345
November	Night	12% 33% 30% 14% 6%	509
December	Night	30% 33% 20% 5%	549

Page generated at 2008-12-24 20:45:18. Version ab11