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Questions and Answers
What type of storm is referred to as a hurricane in the Western Hemisphere?
At what wind speed does a tropical depression become a tropical storm?
Which of the following conditions is necessary for a tropical cyclone to form?
What facilitates the upward movement of air in a tropical cyclone?
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Which phenomenon plays a role in intensifying tropical cyclones according to recent climate trends?
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Where do most tropical cyclones typically form?
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What occurs within the eye of a tropical cyclone?
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Which of the following statements about cyclone tracks is true?
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What is one critical factor that must be present for the formation of a tropical cyclone?
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Which of the following is a reason why names of tropical cyclones are retired?
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What type of damage is primarily caused by storm surges during tropical cyclones?
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Which of the following statements accurately describes the impact of Hurricane Katrina on New Orleans?
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What atmospheric condition is observed to have increased hurricane activity since 1995?
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Which Hurricane caused significant devastation and loss of life in New Orleans in 2005?
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What phenomenon is likely contributing to cyclical patterns of increased hurricane activity in the Atlantic?
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What is one of the major consequences of fresh water flooding during a tropical cyclone?
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Study Notes
Tropical Cyclone Structure
- Tropical cyclones form from easterly waves, which are troughs of low pressure that move slowly on trade winds.
- They develop over oceans between 5 and 30 degrees north of the equator.
Tropical Cyclone Names
- A tropical cyclone is called a hurricane in the Western Hemisphere, a typhoon in the Western Pacific, and a cyclone in the Indian Ocean.
- Tropical cyclones develop from easterly waves.
- Tropical cyclones grow from tropical depressions, which are weak cyclones with maximum wind speeds of 38 mph.
- When the wind speed exceeds 38 mph, the storm is upgraded to a tropical storm.
- Once sustained wind speeds reach at least 74 mph, the storm is classified as a tropical cyclone.
Tropical Cyclone Cross Section
- Tropical cyclones have extremely low pressure and strong pressure gradients.
- The intense convergence and uplift of air results in heavy rainfall.
- Latent heat release provides energy aloft while ocean temperature provides convective energy transfer.
- Tropical cyclones are becoming stronger due to an increase in greenhouse gases in the atmosphere and oceans, which lead to more trapped heat and therefore more convective energy.
Eye of a Tropical Cyclone
- The eye is an area of calm air surrounded by intense spiraling winds.
- The eye is characterized by descending air, which warms and causes water droplets to evaporate.
Positive Feedback in a Tropical Cyclone
- An easterly wave initiates convection.
- Low pressure forms at the surface.
- Warm, moist air spirals inward from the ocean.
- Air rises, expands, cools, and condenses, releasing latent heat into the storm.
- The warmer air rises faster, which drives the inward spiral of air.
- The cycle continues.
Tropical Cyclone Origins and Tracks
- Most tropical cyclones form between 10 and 20 degrees north or south of the equator.
- They follow westward tracks, turning northeastward.
- Tropical cyclones typically fade in the cool westerlies.
- There are no tropical cyclones in the South Atlantic or SE Pacific.
Tropical Cyclone Requirements
- Tropical cyclones need to develop at least 5 degrees from the equator, as the Coriolis effect doesn't exist at the equator.
- They require warm water with temperatures above 26.5 degrees Celsius for a sustained period for the release of latent and sensible heat.
- They need unstable air with a high environmental lapse rate.
- They require weak but uniform steering winds.
- They need a very moist lower atmosphere.
Naming Tropical Cyclones
- Each region has a separate list of names.
- The lists are alphabetical and alternate between male and female names.
- Names are reused after some years.
- Names of serious storms are retired.
- Examples of retired Atlantic hurricane names include Katrina (2005), Andrew (1992), Camille (1969), and Hugo (1989).
Measuring the Impact of Tropical Cyclones
Tropical Cyclone Hazards
- Wind damage - some tropical cyclones produce wind gusts exceeding 200 mph.
- Freshwater flooding - it can extend far inland.
- Earthflows - can occur due to heavy rainfall and saturated soil.
- Storm surge - causes the most serious damage from a cyclone, and can inundate coastal areas.
Impacts on Coastal Communities: The Case of Katrina and New Orleans (2005)
- The eye of hurricane Katrina hit Grand Isle, Louisiana, with sustained winds of 125 mph.
- New Orleans is largely below sea level.
- Levees protect the north and east of New Orleans from Lake Pontchartrain and the Mississippi River.
- Rainwater is pumped from the city through discharge canals.
- During hurricane Katrina, the levees north and east of the city were overtopped or collapsed, allowing water to flood the city.
- Over 80% of the city was underwater at the peak of the flooding.
- Water reached depths of 20 feet in some areas.
- The damage exceeded $100 billion.
- Over 1,300 people were killed in New Orleans alone.
Cyclical Patterns of Atlantic Hurricanes
- Between 1970 and 1994, there was a decrease in Atlantic storms.
- Since 1995:
- Warmer water off the east coast of the US.
- An average of more hurricanes each year.
- An average of more major hurricanes each year.
- 2005 was a record year with 28 storms.
- This is likely due to a cycle in thermohaline circulation.
- The next 20 years are likely to continue to have high hurricane activity.
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Description
Explore the fascinating world of tropical cyclones, including their structure, classification, and naming conventions. This quiz covers essential concepts such as formation, pressure systems, and the differences between hurricanes, typhoons, and cyclones. Test your knowledge on the dynamics of these powerful weather phenomena.
