<P> The main effects of tropical cyclones include heavy rain, strong wind, large storm surges at landfall, and tornadoes . The destruction from a tropical cyclone depends mainly on its intensity, its size, and its location . Tropical cyclones act to remove forest canopy as well as change the landscape near coastal areas, by moving and reshaping sand dunes and causing extensive erosion along the coast . Even well inland, heavy rainfall can lead to mudslides and landslides in mountainous areas . Their effects can be sensed over time by studying the concentration of the Oxygen - 18 isotope within caves within the vicinity of cyclones' paths being very hazardous to people's life . </P> <P> After the cyclone has passed, devastation often continues . Standing water can cause the spread of disease, and transportation or communication infrastructure may have been destroyed, hampering clean - up and rescue efforts . Nearly two million people have died globally due to tropical cyclones . Despite their devastating effects, tropical cyclones are also beneficial, by potentially bringing rain to dry areas and moving heat from the tropics poleward . Out at sea, ships take advantage of their known characteristics by navigating through their weaker, western half . </P> <P> When a cyclone hits it causes PST hazards . PST is an acronym standing for Primary, Secondary and Tertiary . A primary hazard involves destructive winds, debris and storm surge . Secondary hazard is flooding, fires and of course fresh water flooding . Finally Tertiary hazards involves food prices that go majorly up and other long term hazards like water poisoning . </P> <P> A mature tropical cyclone can release heat at a rate upwards of 6x10 watts . Tropical cyclones on the open sea cause large waves, heavy rain, and high winds, disrupting international shipping and, at times, causing shipwrecks . Generally, after its passage, a tropical cyclone stirs up ocean water, lowering sea surface temperatures behind it . This cool wake can cause the region to be less favorable for a subsequent tropical cyclone . On rare occasions, tropical cyclones may actually do the opposite . 2005's Hurricane Dennis blew warm water behind it, contributing to the unprecedented intensity of Hurricane Emily, which followed it closely . Hurricanes help to maintain the global heat balance by moving warm, moist tropical air to the mid-latitudes and polar regions . Were it not for the movement of heat poleward (through other means as well as hurricanes), the tropical regions would be unbearably hot . </P>

What are the dangers associated with tropical cyclones
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