A fluorescent lamp, is a type of electric light (lamp) that uses ultraviolet emitted by mercury vapor to excite a phosphor, which emits visible light. There are two general types, traditional fluorescent and compact fluorescent. This article is about traditional (straight tube shaped) fluorescent lamps.
The purchase price of a fluorescent lamp is often much higher than an incandescent lamp of the same output, and the light from fluorescent lamps looks different to light from incandescent lamps. Fluorescent lamps have a longer rated life and use less energy than an incandescent lamp of the same brightness. A fluorescent lamp can save over US$30 in electricity costs over the lamp’s lifetime compared to an incandescent lamp.
An electric current is applied to mercury vapor inside the tube, causing it to emit ultraviolet (UV) light. A phosphor on the walls of the tube absorbs the ultraviolet light. This causes an electron to jump up to an orbital with a higher energy. When the electron drops back down to its normal orbital, the phosphor re-emits its energy as visible light.
The ballast prevents too much electricity from flowing through the tube. It also starts the lamp with a high voltage for a split second when it is switched on. The ballast is located inside the fixture in traditional fluorescent tube fixtures. In compact fluorescent bulbs the ballast is in or near the base of the bulb. There are two types of ballasts, magnetic and electronic. Magnetic ballasts have mostly fallen out of use, as they are less efficient than electronic ballasts, they cause the bulb to flicker, and they do not start instantly. Electronic ballasts were at one time more expensive than magnetic ballasts, but now the price is about the same.
The average rated life of a fluorescent light bulb is 8 to 15 times longer that of incandescent light bulbs. Fluorescent light bulbs typically have a rated lifespan of 7,000 to 15,000 hours, whereas incandescent lamps are usually manufactured to have a lifespan of 750 hours or 1,000 hours.
The lifetime of any lamp depends on many factors, including operating voltage, manufacturing defects, exposure to voltage spikes, mechanical shock, frequency of cycling on and off, lamp orientation, and ambient operating temperature. The life of a fluorescent lamp is significantly shorter if it is turned on and off frequently. In the case of a 5-minute on/off cycle the lifespan of a fluorescent lamp can be reduced to "close to that of incandescent light bulbs". The U.S. Energy Star program suggests that fluorescent lamps be left on when leaving a room for less than 15 minutes so that this problem does not happen. If the light must be switched on and off often, Cold cathode fluorescent lamps can be used. Cold cathode fluorescent lamps are designed for many more on/off cycles than standard lamps.
The mercury inside the tube is toxic and makes these bulbs hazardous waste. The bulbs must be taken to a recycling center after they stop working. During normal use, the mercury cannot escape, although it will escape if the bulb is broken. If a single bulb breaks, it is not usually a problem. It is recommended to open windows to air out the room, and to clean up broken glass with duct tape instead of a vacuum cleaner.
Many people and businesses do not want to use fluorescent lamps due to their mercury content. Halogen, LED, and traditional incandescent bulbs are possible alternatives.
LED tubes can be installed in fluorescent tube fixtures, but sometimes an electrician needs to rewire the fixture first to remove the ballast.
My December
My December is Kelly Clarkson's third album. The songs "Never Again", "Sober" and "One Minute" have been released.
Tropical Storm Chantal (2007)
Tropical Storm Chantal was a very short-lived storm in the northern Atlantic Ocean that stayed away from land during most of its existence. It was also the third named storm of the 2007 Atlantic hurricane season. The stormed formed from a non-tropical system between Bermuda on Cape Cod, Massachusetts that developed on July 31 with good conditions for further development. The storm had maximum sustained winds of 50 mph (80 km/h) and began to move quickly northeastwards into colder water temperatures. When convection began to decrease, the National Hurricane Center stopped sending out advisories on August 1 when Chantal began to turn into an extratropical cyclone. Later, the remnants moved over southeast Newfoundland, before moving into the Arctic Ocean.
An area of thunderstorm activity developed on July 28 about 100 miles (160 km) east of the Bahamas which was associated with a weak low pressure system. It moved north-northeastward, into poor environmental conditions which left the system disorganized. However, conditions then were forecasted to become better for development, and by July 29 the National Hurricane Center stated that it had "potential for tropical or subtropical development." On July 30, the low passed to the west of Bermuda as it continued moving northeastward, under the effects of a large mid-latitude trough. The system contained an exposed low-level circulation, which from time to time passed under a thick area of convection to its northeast. By early on July 31, ship reports and QuikSCAT observations detected winds of 35 mph (55 km/h), and the center was well-involved enough with the convection for the National Hurricane Center to name it as "Tropical Depression Three" while it was located about 270 miles (435 km) north-northwest of Bermuda, or about 445 miles (710 km) south-southeast of Chatham, Massachusetts.
By six hours after development, the depression had of a somewhat exposed low-level center with deep convection taking up most of the northeastern semicircle. Located over sea surface temperatures of about 80º F (27º C), one forecaster said the depression had "a small window of opportunity... for it to reach tropical storm strength before transitioning to an extratropical cyclone." The system organized further, and based on satellite pictures and QuikSCAT data, the National Hurricane Center upgraded the depression to Tropical Storm Chantal at 1215 UTC on July 31 while located about 330 miles (530 km) south of Halifax, Nova Scotia. By three hours later the system formed a well-defined curved banding features, and Chantal reached maximum systained winds of 50 mph (80 km/h) at 40.2º N. The storm speed up northeastward into an area of cold waters and cooler air, and early on August 1 the National Hurricane Center gave out its last advisory on Chantal as it began extratropical transition.
After becoming an extratropical cyclone, Chantal managed to keep scattered convection near its center, though its main area of convection and clouds moved to its north. On August 1, the cyclone made landfall on Newfoundland along the Avalon Peninsula, and by late in the day the extratropical remnants of Chantal were about 265 miles (425 km) northeast of St. John's, Newfoundland and Labrador and moving northeastward at 44 mph (70 km/h).
The weather system that would later become Chantal began to affect Bermuda on July 30. It caused some thunderstorms. The next day, it caused heavy rainfall that reached r2.12 inches (53.8 mm) at the Bermuda International Airport. Winds on the island reached 45 mph (72 km/h) because of the weather system. After Chantal passed Bermuda, a ship with the call sign of "C60Y4" recorded winds of 37 mph (59 km/h).
Shortly after the system became a tropical storm, the Atlantic Storm Prediction Center of Canada sent out gale warnings for the waters off of Newfoundland. The Newfoundland Labrador Weather Office also issued warnings for heavy rain.