The Science Behind Israeli Sirens

Warning sirens have sounded over 4,000 times in Israel over 45 days of fighting with the Gaza Strip. When do sirens sound automatically and when manually? Why do false alarms occur and why do sirens sometimes not sound when rockets are fired?

Warning sirens have sounded over 4,000 times in Israel over 45 days of fighting with the Gaza Strip. It only takes a few seconds to operate the sirens;...