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Web page updated: 4/2/2012
Arnhem South measuring location
The nomogrammometer is a “dash-board“ display with instanteneous values. The yellow horizontal line shows the sky brightness at this moment.
The red horizontal line is the natural level without any light pollution under a clear cloudless sky without moon.
The factor light pollution indicates by how many the the sky is brighter than the natural level.
The sky brightness is measured in millicandela per m2 overhead the measuring location.
The number of visible stars >45° is the number of stars that are visible from 45°altitude above the horizon up to the zenith (right above an observer), as only these are visible from an urban area.
The green line shows the actual measured values till now. The time is shown on the lowest axis and runs from 12 hours (GMT) at noon to 12 hours (GMT) the next day. During daytime the green line is not visible as the sky is much brighter than the light meter can measure. Only after sunset the values come within range of the light meter.
The yellow line shows the theoretical level with the sun above the horizon and the blue line shows theoretical level with the sun below the horizon.
The red line shows the theoretical level when the moon is above the horizon. Top right the phase of the moon is shown, which is valid at midnight (24 hours GMT). The left axis show the sky brightness level in in millicandela per square meter (mcd/m2).
Measuring location Arnhem-South
Monitoring
Measuring equipment
Trend of the past hours
Lumineux Consult has installed a light meter at the location Arnhem-South (in the Netherlands). It monitors the sky brightness continuously. On this page you can - after sunstet - see the actuale values online. Every 10 seconds a measurement is made and every minute the graphs on this page are refreshed.
Actual measuring data location Arnhem-South Local time = GMT + 2 (summer)
The goal of the monitoring answers the follwing questions:
- How often is it how bright?
It shows that with cloud cover the light pllution is about a factor 10 higher. World wide there are hardly any measuring data about this.
- Does light pollution increase?
To what extent is this increase due to the increase in outdoor lighting and urbanisation?
→ Click for overviews of the measuring results:
The light meter (SQM) is installed in a weather proof cabinet with an acryllic globe including an anti dew heating and a regulator. Due to this the light meter functions properly under all weather conditions (including snow).
The SQM meaures overhead with a viewing angle of 20°. The SQM is connected to a computer, which send the measuring data to this webpage.
The measuring location lies at the south border of the city of Arnhem (the Netherlands).
Data analysis
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© Lumineux Consult
