Located at 22.2°N and 77.2°W, Hurricane Irma, a Category 4 hurricane, is located moving west at 12 mph with a minimum pressure of 924 millibars.

Millibars is a term many people aren’t familiar with. In fact, some people’s immediate instinct might be to panic when they see a high number next to the term. However, in its simplistic term, millibars, shortened to “mb” is a measuring unit used to determine the pressure of a hurricane. Many people are unfamiliar that the higher the number is, the better.

A minimum pressure of 927 mb means that the air pressure is really low – when a storm is not present, the normal air pressure is 1013 mb.

While a high number may cause panic, a low air pressure is actually worse. A low air pressure allows for the hurricane to develop more quickly, which will make it increase into higher categories.

A barometer measures the air pressure, but, at the moment, the pressure is lower than one atmosphere, which is the average air pressure at sea level. This is causing other stormfronts such as Katia, Harvey, and Jose to form. While the hurricane has decreased in category size, the 150 mph winds can still cause disasters of catastrophic proportions. Hurricane Irma is predicted to go down as one of the worst hurricanes in the history of the United States.

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