The term 'tropical' refers to both the geographic origin of these systems, which form almost exclusively in tropical regions of the globe, and their formation in maritime tropical air masses. The term 'cyclone' refers to such storms' cyclonic nature, with anticlockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. Depending on its location and intensity, a tropical cyclone can be referred to by names such as 'hurricane', 'typhoon', 'tropical storm', 'cyclonic storm', 'tropical depression', or simply 'cyclone'.
Cyclone Tracy was a tropical cyclone that devastated Darwin, Australia, from December 24 to December 25, 1974. It was recorded by The Age as being a "disaster of the first magnitude...without parallel in Australia's history." It killed 71 people - the official death toll was revised upwards from 65 to 71 in March 2005 - and destroyed over 70 percent of Darwin's buildings, leaving over 20,000 people homeless. Most of Darwin's population was evacuated to Adelaide, Whyalla, Alice Springs and Sydney, and many never returned to Darwin. The town was subsequently rebuilt with modern materials and techniques. Cyclone Tracy was at least a Category 4 storm, although there is evidence to suggest that it had reached Category 5 intensity when it made landfall at Darwin.
This photograph shows the bowl-shaped eye of Typhoon Yuri in the western Pacific Ocean just west of the Northern Mariana Islands. The eye wall descends almost to the sea surface, a distance of nearly 45,000 feet (13 800 meters). In this case the eye is filled with clouds, but in many cases the sea surface can be seen through the eye. Yuri grew to super typhoon status, packing maximum sustained winds estimated at 165 miles per hour (270 km/h). The storm moved west toward the Philippines before turning northeast into the north Pacific Ocean, thus avoiding any major landmass.