The lamps are cooled to prevent overheating and a heating system is activated when the temperatures drop below zero Centigrade whilst the lights are off. The xenon 6000 watt lamps were chosen for their longevity, around 1,200 hours. Since their rotation sweep is 90°, they are synchronized to form a double beam in a cross that pivots around 360°. They are operated by automatically piloted computer programs. The beacon, sending out two light beams with a reach of 80 kilometres, is composed of 4 "marine" motorised projectors. On 31 December 1999 at the approach of midnight, the entire world will discover the beacon and the Tower's sparking lights. In 2020, the 28 projectors that illuminate the steps in the outstretched portions of the four pillars will be replaced to reduce the installed power by 80%. In December 2019, the four 2000W projectors that had illuminated the antenna since 1985 were replaced by LED versions that are 10 times less powerful and consume 10 times less energy. The last operation took place in spring 2019.Ĭontrary to popular beliefs, the Tower’s nightly illumination, it’s golden glow, only represents about 4% of the monument’s annual energy expenses. Since that time and every four years, a team of SETE technicians has replaced the 336 projector bulbs that wrap the Eiffel Tower in golden light every evening. Their improved output of light preserves all the beauty of the overall appearance. an energy consumption saving of around 40%. In 2004, they were replaced by projectors with an electrical power of 600 watts as opposed to the previous 1KW, i.e. This is activated upon nightfall by the sensors. The colors are also produced through gas excitations of the gas molecules in the atmosphere, particularly nitrogen.The projectors are turned on in under 10 minutes. Seen from above, lightning storms also produce less well-known emissions of blue or red light above the clouds, known as jets and sprites. The distinctive blue-white color of lightning is caused by light emitted as the electrons drop back to their original energy states. Nitrogen, the dominant gas in the atmosphere, is excited by this strong flow of energy, its electrons moving to higher energy states.
Lightning is visible as a flash of light because of both incandescence (due to its high temperature it glows blue-white) and luminescence (excitation of nitrogen gas in the atmosphere). The flash reaches temperatures of about 30,000 K.
In successive discharges, surrounding pockets of charge in the cloud follow this path to earth.
#Blue and purple lightning free#
Once the first of these leaders reaches the ground, the electrostatic forces are free to flow to earth in a brief and high-voltage discharge. In a chain reaction, "leaders" form tracks spreading like branches through the air below the cloud, breaking down the air molecules into charged particles. For a time, the air insulates them from each other, but then the electrostatic difference reaches a point where the electric flash begins to form. Pockets of positive and negative charge develop within the cloud, and eventually reach a size big enough to induce an opposite charge at a point on the ground below. Electrical excitation is at play in both the lightning and the bridge, which is lit with vapor lamps.įorked lightning is a huge discharge of electricity between heavy cumulonimbus clouds and the ground. Above right, lightning dances across the charged skies over Sydney Harbour and the Harbour Bridge.
0 kommentar(er)
