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Sound sample ⓘ A civil defense siren is a siren used to provide an emergency population warning to the general population of approaching danger. Initially designed to warn city dwellers of air raids (air-raid sirens) during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes (tornado sirens).
A British air raid siren from the Second World War. All clear is the signal, generally given by an air raid siren, which indicates that an air raid or other hazard has finished and that it is safe for civilians to leave their shelters; it is commonly used in radios as well.
Mechanical sirens blow air through a slotted disk or rotor. The cyclic waves of air pressure are the physical form of sound. In many sirens, a centrifugal blower and rotor are integrated into a single piece of material, spun by an electric motor. Electronic sirens are high efficiency loudspeakers, with specialized amplifiers and tone generation ...
Russia has launched the biggest air attack on Ukraine since the beginning of its full-scale invasion, the Ukrainian military told CNN, with an unprecedented number of drones and missiles fired at ...
Attack warning RED! Attack warning RED! The message would be sent to the police by the telephone system used for the speaking clock, who would in turn activate air attack sirens using the local telephone lines. The rationale was to tackle two problems at once; it reduced running costs (it would most likely be used only once in its working life ...
Russia launched a “massive” missile and drone attack aimed at energy infrastructure across Ukraine at the start of the week, marking the biggest air assault since the war began, Ukrainian ...
Brett Willis, Los Angeles Fire Department's battalion chief over air operations, said there were at least three sizes of helicopters flying during the attack, including ones that can hold 480 ...
A United States Army Air Forces B-24 Liberator after an airstrike on Saint-Malo, France in 1944. An airstrike, air strike, or air raid [1] is an offensive operation carried out by aircraft. Air strikes are delivered from aircraft such as blimps, balloons, fighter aircraft, attack aircraft, bombers, attack helicopters, and drones.