Lesson in Color Temperature 101. -- copcar dot com's Discussion Board

[ Show ]

Support VoyForums

[ Shrink ]

VoyForums Announcement: Programming and providing support for this service has been a labor of love since 1997. We are one of the few services online who values our users' privacy, and have never sold your information. We have even fought hard to defend your privacy in legal cases; however, we've done it with almost no financial support -- paying out of pocket to continue providing the service. Due to the issues imposed on us by advertisers, we also stopped hosting most ads on the forums many years ago. We hope you appreciate our efforts.

Show your support by donating any amount. (Note: We are still technically a for-profit company, so your contribution is not tax-deductible.) PayPal Acct: Feedback:

Donate to VoyForums (PayPal):

[ Login ] [ Main index ] [ Search | Check update time | Archives: 1, [2], 3, 4, 5, 6 ]

Subject: Lesson in Color Temperature 101.

Author:
Project Greenlight

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Date Posted: 12:50:07 12/12/02 Thu
In reply to: Vtpapa 's message, "Blue lights, etc." on 11:42:50 12/12/02 Thu

"Recently I learned that one of the sheriff's departments in VT is asking the legislature to allow red and blue lights on police cars because blue light "washes out" in sunlight. I'm not so sure about the validity of that position."

That would make sense. Daylight is not "white" light. It is actually very blue. The "color temperature" of all forms of visible light can be measured in units of "kelvin". Direct sunlight is "cool" and measures around 5600 degrees kelvin (5600K). The "warm" incandesent light bulb in your house has much more red in it and emits light at about 2500K. Sodium vapor street lights are near the bottom of the scale at about 2200K and a heavily overcast day in winter is closer to the top at about 7500K. So it makes sense that in daylight, especially gloomy, extra-blue daylight, that the effectiveness of a blue light would be diminished. Transversly, the effects of a red light under sodium vapor lights would be diminished. So the green light is likely the best choice for round the clock visability. Class dismissed.

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Replies:

Subject	Author	Date
and they joked about gumdrop lights before...	matt	18:15:28 12/12/02 Thu


great a lime on top of a lemon (NT)	Matt	18:17:30 12/12/02 Thu