what is in orange street lamps and why is it used?

Answer 1

sodium

Answer 2

Today, street lighting commonly uses high-intensity discharge lamps, often HPS high pressure sodium lamps. Such lamps provide the greatest amount of Photopic illumination for the least consumption of electricity. However when Scotopic/Photopic light calculations are used, it can been seen how inappropriate HPS lamps are for night lighting. White light sources have been shown to double driver peripheral vision and increase driver brake reaction time at least 25%. When S/P light calculations are used HPS lamp performance needs to reduced by a minimum value of 75%. This is now a standard design criteria for Australian roads.
For placements where light pollution is of prime importance (for example an observatory parking lot), low pressure sodium is preferred. Sodium emits light on only one wavelength, and therefore is the easiest to filter out.

One consequence of widespread public lighting is that on cloudy nights, cities with enough public lighting are illuminated by light reflected off the clouds. As sodium vapor lights are often the source of urban illumination, this turns the sky a tinge of orange. If the sky is clear or hazy, the light will radiate over large distances, causing large enough cities to be recognizable by an orange glow when viewed from outside the city.

The first city to have electric street lights was Godalming, UK (1881).

Answer 3

Orange street lamps show up better in the fog - that's the theory anyway

Answer 4

sodium which glows yellow/orange when ionized by an electric current.
It is used because it is cheap and has a certain amount of penetrating power over blue/white lamps

Answer 5

The first electric street lights were white but they produced dark shadows, the sodium light is more diffuse.

Answer 6

A type of Primate?...

oh you refer to the Sodium street lamps, in the zoology section.

A range of sodium light bulbs that give off a orange light. SON lamps have a lamp life of up to 25000 hours and are used for street and flood lighting applications.

LPS Lamps (Low Pressure Sodium), also known as SOX Lamps (Sodium OXide), consist of an outer vacuum envelope of glass coated with an infrared reflecting layer of indium tin oxide, a semiconductor material that allows the visible light wavelengths out and keeps the infrared (heat) back. It has an inner borosilicate 2 ply glass U shaped tube containing sodium metal and a small amount of neon and argon gas Penning mixture to start the gas discharge, so when the lamp is turned on it emits a dim red/pink light to warm the sodium metal and within a few minutes it turns into the common bright orange/yellow color as the sodium metal vaporizes. These lamps produce a virtually monochromatic light in the 590 nm wavelength. As a result, objects have no color rendering under a LPS light and are seen only by their reflection of the 590 nm light (orange).

LPS lamps are the most efficient electrically powered light source when measured for photopic lighting conditions. — up to 200 lm/W. As a result they are widely used for outdoor lighting such as street lights and security lighting where color rendition is viewed by many to be less important. LPS lamps are available with power ratings from 10 W up to 180 W, however length increases greatly with wattage creating problems for designers.

LPS lamps are more closely related to fluorescent than High Intensity Discharge lamps, since they have a low–pressure, low–intensity discharge source and a linear lamp shape. Also like fluorecents they do not exhibit a bright arc as do other HID lamps, rather they emit a softer luminous glow, resulting in less glare.

Another unique property of LPS lamps is that, unlike other lamp types, they do not decline in lumen output with age. As an example, Mercury Vapor HID lamps become very dull towards the end of their lives, to the point of being ineffective, whilst still drawing their full rated load of electricity. LPS lamps, however, do increase energy usage towards their end of life, which is usually rated around 18,000 hours for modern lamps.

High pressure sodium (HPS) lamps are smaller and contain some other elements (for example, mercury), produce a dark pink glow when first struck, and produce a pinkish orange light when warmed up. The sodium D-line is the main source of light from the HPS lamp, and it is extremely pressure broadened by the high sodium pressures in the lamp, hence colors of objects under them can be distinguished. This leads them to be used in areas where good color rendering is important, or desired.

High pressure sodium lamps are quite efficient — about 100 lm/W, up to 150 lm/W, when measured for Photopic lighting conditions. They have been widely used for outdoor lighting such as streetlights and security lighting. Understanding the change in human colour vision sensitivity from Photopic to Mesopic and Scotopic is essential for proper planning when designing lighting for roads.

Because of the extremely high chemical activity of the high pressure sodium arc, the arc tube is typically made of translucent aluminum oxide (alumina). This construction led General Electric to use the tradename "Lucalox" for their line of high-pressure sodium lamps.

Answer 7

It's a special gas in them and they were made like that because they were supposed to shine through the fog. Never did work properly though. They are being replaced with white lights now because we don't get fog like we used to.

Answer 8

Sodium vapour. Cheap and efficient. Being replaced slowly by high pressure sodium which gives a whiter light.

Answer 9

The type of bulb, which had sodium in it, just like everyone else said.

Answer 10

The bulbs are filled with sodium which makes them last longer.

Answer 11

Tango