Night Light Density


Night Lights of Montgomery County

Abington Township is on the eastern end of Montgomery County (screen right). Abington is at the crossroads between urban density and the suburbs. The Commissioners of the Township must factor-in the impact on light on the health, quality of life and night lights as new developments are planned. IDSA has an online model lighting ordinance that describes how to grow in a smart way.

This satellite image of our area is provided by the National Oceanic & Atmospheric Administration (NOAA). Pure white is the most intense areas of urban light. As the image gets darker, the lights dim and the night sky emerges for those on the ground.

In addition to the impact on star-gazing, the urban aura of light may also have an impact on our health. Initially, it was thought that only bright light was effective in shifting circadian rhythms. However, recent data indicate that even low levels of illuminance, such as 100 lux, can shift rhythms, although not as strongly as higher levels of illuminance.

The body temperature rhythm is the most commonly studied circadian variables; often the time of the lowest point in the temperature rhythm is defined as a "hand" of the body clock. Shifts in the timing of circadian rhythms can cause initial insomnia, early morning awakening, or excessive sleep.

According to Environmental Health News, the light pollution may be changing disease risk patterns. The evidence suggests researchers should consider this when conducting future studies of how diseases spread. Many potentially fatal or disfiguring tropical diseases are caused by parasites that are transmitted to humans by the bite of a specific insect carrier, which often occurs at night. Insects are generally attracted to artificial lights. The lights interrupt and confuse the insects' normal night-time navigational cues, such as moonlight. Insects may also have adapted their routine, using lights as signs that humans are near.

Sources and Links:
USGS National Atlas
NOAA Satellite and Image Services
Daily Satellite Images from FlashEarth

The World Atlas of the Artificial Night Sky Brightness

Interrnational Dark-Sky Association
The Effects of Light on Circadian Rhythms, Sleep and Mood

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