But, be wary of claims that Irma is the ‘worst’ hurricane in the Atlantic in history. (The ‘Atlantic’ is defined as the basin extending from the open ocean, including the Gulf of Mexico and the Caribbean Sea.) No doubt, it’s among the worst and will rank in the top 10 hurricanes in recorded history, but reliable hurricane history only goes back loosely to the 1890s.
The satellite era of recording every hurricane only goes back to the early 1960s. Planes weren’t used to measure minimum central pressure until about 1945. Some hurricanes slipped through the cracks of being observed prior to 1960 and others were not properly sampled before WWII.
Our recorded hurricane history is thus extremely limited so this can not be placed in league with the countless hurricanes in the tens of millions of years before we got here. To claim any superlative in science as being, “the worst” is inherently inaccurate… But in the spirit of our very brief human time-scale history and the human need to seek validation, we can say Irma is a big one.
Hurricane Allen in 1980 packed strongest winds in Atlantic basin with max sustained of 190mph. (Compared to Irma’s 185mph.)
However, a better way to measure storm intensity is looking at the air pressure of a hurricane — especially its minimum central pressure. Hurricane Wilma packed the lowest pressure in Atlantic basin with 882mb (compared to Irma’s 914mb at its peak.)
Why do we look to its minimum central pressure instead of peak wind speed in judging a hurricane’s strength? Because, it’s impossible to sample what the winds are doing at all times inside a storm, as we simply don’t have a large network of instruments in the ocean measuring them.
With the exception of a few buoys here and there, we rely on airplane recon to take measurements. If the system peaks while there’s no airplane inside the hurricane in the strongest quadrant, that wind speed could go unobserved.
However, the air pressure in the core is more easily measured but faces the similar observation limitations. (Satellites can only estimate barometric pressure.)
Pressure also indicates depth of a cyclone. The deeper (lower the pressure) the stronger.
Irma follows Ivan, with a minimum central pressure at peak of 914mb, making it #10 strongest in Atlantic basin. ‘Recorded history’ only goes back to WWII when planes were 1st used for recon. Pre-1960, there were no weather satellites to see far.
Read more at KHOU