At the present time, one of the worst storms in American history, Tropical Storm Harvey (seen below at full strength), is laying waste to east Texas. It also generated the worst hurricane to hit Texas in fifty years and is causing unprecedented flooding in the city of Houston. The neighbouring state of Louisiana is also beginning to feel its effects. Harvey, which made first landfall as a category 4 hurricane, has brought flash floods and extreme winds across the land; claiming lives, destroying the environment, and damaging the long term economy. Tropical storms can include hurricanes as was originally the case here, or cyclones and typhoons, or a combination of all three. With them comes heavy rainfall, mudslides, and floods.
As tropical storms need intense heat in which to form, they only occur either just to the north or south of the equator, where the sea temperatures can reach up to 27ºC. Generating where the air above a warm sea rises, it is this combination of temperature between the water and the sky that causes the sort of atmospheric low pressure which can spark a tropical storm.
When superheated air rises, it begins to spin, forming the eye of a forthcoming storm. Once that air has risen it cools rapidly, condensing into massive clouds. Compacted air within these clouds creates areas of intense low pressure. In turn, that low pressure sucks at the air around it, creating incredibly strong winds. Only when the storm blows inland, where the air and ground cover are cooler still, do these major weather events begin to blow themselves out.
To make storm weather data easier to track and record accurately for future meteorologists and historians, tropical storms are given names. These names are alphabetical and alternate between male and female. It means that the next tropical storm in America will be given a female name beginning with the letter ‘I’.
Due to the erratic nature of the air pressure near the equator, it is very difficult to accurately predict the path a tropical storm will take. This means that evacuating people and livestock from a threatened area is not easy. For example, when Hurricane Katrina hit New Orleans in August 2005, over 1,800 people died and 300,000 homes were destroyed before the area could be completely evacuated.
The social impact on an area hit by a tropical storm can often be major and long term. Power is often cut, with vast populations being left without electricity for many weeks, if not months after the storm has passed. Homes have to be abandoned and many will be destroyed entirely. Mass migration from the affected area leaves entire communities temporarily, or permanently, homeless. Neither is it certain that affected communities will return entirely. In fact it is more probable that a significant number will not. It is estimated that around 50,000 of the population left or did not return to New Orleans after Katrina. What will happen to Houston remains to be seen.
As well as homes, businesses, towns, farms and power stations are all vulnerable to destruction. The looting of abandoned homes and shops can also come from criminal and desperate locals alike. On a national level, resources such as petrol can’t be taken safely into a hurricane hot spot, which means fuel prices rise, as does the cost of food and clean water. Houston will be a prime example, as it produces a great quantity of the oil America runs on, let alone exports. Tourists also stop coming to the area, and as most places on the equator rely heavily on tourists from countries with cooler climates, the economic impact can be extreme. An industrial city like Houston might not feel this, but New Orleans certainly did.
If a tropical storm burns itself out quickly, then the environmental, social and economic costs can be quickly mitigated. When storms of the ferocity of Hurricanes Katrina and Harvey hit, however, the costs are far higher- and can take decades to overcome.
Dr Kathryn Bates is a graduate of archaeology and history. She has excavated across the world as an archaeologist, and tutored medieval history at Leicester University. She joined the administrative team at Oxford Open Learning twelve years ago. Alongside her distance learning work, Dr Bates is a bestselling novelist, and an itinerant creative writing tutor for primary school children.