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Cyclones Vs. Tsunamis

Cyclones and tsunamis are naturally occurring phenomena that can pose threats to human life and property. The extent to which these forces of nature impact people and societies depends on their strength and type ̵1; for instance, like tsunamis, tropical cyclones can have particularly powerful effects. To understand these effects as well as the similarities and differences between cyclones and tsunamis, it is useful to have a basic working knowledge of how, why and where they occur.

Cyclones: The Facts
- In some parts of the United States, people use the term ̶0;cyclone̶1; to refer specifically to tornadoes or dust devils. But in a broader meteorological sense, a cyclone is any type of system that rotates -- areas of low atmospheric pressure possessing circulating wind patterns. In the Northern Hemisphere, winds flow around cyclones in a counterclockwise direction; in the Southern Hemisphere, winds spiral around cyclones in a clockwise direction. Associated with rising air, cyclones are unstable weather conditions, ranging from mere clouds and drizzle to the violent wind, heavy showers and lightning that accompany hurricanes.
Tsunamis: The Facts
- Tsunamis consist of fast-moving, potentially far-reaching waves which form when a sizable volume of water in an ocean or occasionally a lake is abruptly displaced. Most often, underwater or coastal earthquakes are the trigger for tsunamis, but rarely, undersea volcanoes, landslides or meteors can generate them. In the open ocean, tsunamis can travel at speeds approaching 600 miles per hour. At this stage, they are low in height, and barely detectable to boats. As they approach a coastline, however, they slow down and their height increases drastically, producing a towering wall of water.
Types of Cyclones and Tsunamis
- Different kinds of cyclones and tsunamis exist. Cyclones can be categorized as tropical, subtropical, mid-latitude or mesoscale. Tropical cyclones, while not the most common type, may be the most familiar, as they consist of typhoons, hurricanes, tropical storms and depressions, which form over warm ocean water in the tropics. Mid-latitude cyclones form at higher latitudes, while subtropical cyclones are a cross between the tropical and mid-latitude variety. Mesocylones entail smaller-scale, localized rotating storms such as supercells, tornadoes, waterspouts and dust devils.
  
  Scientists categorize types of tsunamis based on the distance from their source of generation to their point of impact. Local tsunamis strike within 60 miles (100 kilometers) of their source, arriving in less than an hour. Regional tsunamis strike 60 to 600 miles (about 100 to 1,000 kilometers) from their source, arriving in one to three hours. Distant tsunamis strike more than 600 miles (1,000 kilometers) from their source, taking three or more hours to arrive.
Fundamental Similarities and Differences
- Tsunamis only affect coastlines, and while tropical cyclones also exert their strongest effects on coastal areas, cyclones as a whole affect inland areas as well as the open sea. Cyclones originate in the Earth̵7;s atmosphere, while tsunamis originate underwater. Tsunamis always require oceans or other large bodies of water in order to form, as do tropical and subtropical cyclones. Scientists can predict cyclones much further in advance and with a greater degree of accuracy than they can tsunamis, which form as abruptly as an earthquake strikes. Meteorologists and climatologists study cyclones, while geologists and seismologists study tsunamis.

Nature