1) Cyclones, also known as hurricanes or typhoons, are powerful tropical storms characterized by low-pressure centers and strong winds.

2) Mountains are important water sources, as they capture and store precipitation, feeding rivers and supporting ecosystems downstream.

3) The fall of the Berlin Wall in 1989 symbolized the end of the Cold War and the reunification of East and West Germany.

4) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.