Decipher the strange storm named Harvey

Why did Hurricane Harvey level up so fast? Why does it stop in Houston? Why does it cause so much rainfall? Explanation of Scientific American page.

Hurricane Harvey submerged southeast Texas under meters of water after days of pouring rain. Experts say the storm stopped at a place longer than any previous tropical storm.

Meteorologist Jeff Masters explains some of the unusual elements of Hurricane Harvey:

1. Why did Hurricane Harvey rise from level 1 to level 4 so fast?

Last Wednesday (August 23), Harvey was just a tropical depression, but overnight it quickly formed a stormy eye. This is a very fast speed.

The landlady in Fulton City, Texas, looks for items still in her home that were destroyed by Hurricane Harvey - (Photo: REUTERS).

By Friday, it continued to rise from a Category 1 storm to level 4 (American hurricane scale). This happens because Harvey travels through an extremely warm sea area. The temperature here is 1-2 degrees Fahrenheit (ladder due to the US temperature) compared to the surrounding Gulf of Mexico water, which is also higher than average 1-2 degrees F.

The warmer the water is, the greater the energy it transmits for a storm. Super typhoon Katrina, once devastating the city of New Orleans in 2005, also increased to level 4 in the same way, as it passes through a warm water on the Gulf of Mexico.

2. Why is Harvey anchored in Texas?

The storms are spiral structures with anticlockwise wind, but their path itself is controlled by larger winds in the atmosphere.

In the case of Harvey, a high-pressure system in the southeastern United States pushes it in one direction, but another high-pressure system in the southwest pushes it in the opposite direction.

'Both systems have the same strength and elimination, resulting in Harvey standing still. It's rare for the two high-pressure areas to have the same power to appear at the ends of a storm ' - Masters commented.

3. Can Harvey move back to the Gulf of Mexico?

The high-pressure area in southeast America pushed Harvey to the west, but the high-pressure area in the southwest pushed it to the east. At some point, one of the two high-pressure areas will win the other. Therefore, Harvey can go back to the sea, which is where it comes from.

The national weather forecast agency said this could happen this weekend.

4. Why does Harvey cause a lot of rain when it is no longer on the sea?

Typically, a storm absorbs moisture from the ocean and then rains down the ground within its sphere of influence.

However, Harvey vented so many countries throughout southeast Texas that it could draw back this water, and then poured it down.

The flooded area is so large that it can be seen as part of the ocean, providing moisture to the storm Harvey.

'You only need about 50% of the flooded area for this to happen. Clearly in Texas we have more than that ' - Mr. Masters explained.

5. Can Harvey stay there like a rain machine?

Mr. Master acknowledged that meteorologists cannot answer this question.'If it stays there, can it remain for a long time? That's an interesting theoretical question, but we really don't know. '

On August 29, the sky still blackened the storm caused by the hurricane Harvey - (Photo: REUTERS).

6. Why does Harvey cause more rain at night?

This phenomenon is quite common for big storms: weakening during the day and stronger at night.

'At night, the elevated air area decreases the temperature causing instability. It increases the flow of air in the upward direction in the storm system, absorbing more moisture from the sea surface or wetland ' - Masters explained.

7. Why does Harvey make the coastal area flooded even though the sea level is not high?

This is also quite a strange thing. Sea level rise is often a dangerous aspect of the tropical storm system.

Sea level rise in Hurricane Katrina in 2005 engulfed New Orleans, Hurricane Sandy flooded New York City and New Jersey .

The sea water did not rise so high in the case of Hurricane Harvey, but the country still engulfed many areas of the Texas coast. Expert Masters call this 'combined flood'.

With too much rainfall, the rivers in the mainland overflowed and flowed to the sea, while sea level rise also poured into the mainland. These two streams meet at the shore and cause water to rise simultaneously.

The terrain and elevation in each area can make the 'combined flood' worse . 'For example, in Galveston, the sea is only about 0.91m, but in fact it surges to 2.74m,' said Masters.