Hurricanes

  • Form over warm ocean waters near the equator
  • Warm, moist air over the ocean rises upward
  • less air left near the surface
  • an area of lower air pressure below
  • Air from surrounding areas with higher air pressure pushes in to the low pressure area
  • "new" air becomes warm and moist and rises, too
  • As the warmed, moist air rises and cools off, the water in the air forms clouds
  • Storms that form north of the equator spin counterclockwise. Storms south of the equator spin clockwise.
  • storm system rotates faster and faster, an eye forms in the center
  • Tropical storm: winds in the rotating storm reach 39 mph
  • Tropical cyclone aka hurricane: when the wind speeds reach 74 mph
Hurricane categories table
Show All

Category
Wind Speed (mph)
Damage at Landfall
Storm Surge (feet)
1
74-95
Minimal
4-5
2
96-110
Moderate
6-8
3
111-129
Extensive
9-12
4
130-156
Extreme
13-18
5
157 or higher
Catastrophic
19+
Source: https://spaceplace.nasa.gov/hurricanes/en/
Next:
Mega hurricane trend