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Climate Change Drives Bigger, Wetter Storms -- Storms Like Florence (npr.org)
Rebecca Hersher, reporting for NPR: Hurricane Florence is moving relentlessly toward the Southeastern U.S. It's a large, powerful cyclone that will likely bring storm surge and high winds to coastal communities. But climate scientists say one of the biggest threats posed by Florence is rain. "Freshwater flooding poses the greatest risk to life," explains James Kossin, an atmospheric scientist for the National Oceanic and Atmospheric Administration and the University of Wisconsin, Madison. And Florence could cause extensive freshwater flooding for two reasons. First, Florence is moving slowly, and could all but stop when it reaches land. "The storm could be over North Carolina and traveling incredibly slowly -- on the order of just a few miles per hour," explains Kossin, who says an official from the city of Charlotte, N.C., contacted him about rainfall projections for that city.
If Florence stalls over the Southeast, it would be reminiscent of Hurricane Harvey, which spent days dumping rain on the Houston region last year. Some areas ended up with more than 60 inches, a catastrophic amount of water that shut down the entire region and resulted in at least 93 deaths. Slow-moving storms like Harvey are getting more common. A study published earlier this year by Kossin found that tropical cyclones around the world have slowed down 10 percent in the last 70 years. "We're seeing that in every ocean basin except the northern Indian Ocean," says Kossin, possibly because climate change is causing the wind currents that hurricanes ride to slow down. If Florence slows down and stalls when it hits land, it will the latest example of that trend. Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colo., says global warming also affects the size and intensity of storms like Florence.
If Florence stalls over the Southeast, it would be reminiscent of Hurricane Harvey, which spent days dumping rain on the Houston region last year. Some areas ended up with more than 60 inches, a catastrophic amount of water that shut down the entire region and resulted in at least 93 deaths. Slow-moving storms like Harvey are getting more common. A study published earlier this year by Kossin found that tropical cyclones around the world have slowed down 10 percent in the last 70 years. "We're seeing that in every ocean basin except the northern Indian Ocean," says Kossin, possibly because climate change is causing the wind currents that hurricanes ride to slow down. If Florence slows down and stalls when it hits land, it will the latest example of that trend. Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colo., says global warming also affects the size and intensity of storms like Florence.
The slow movement of Florence and possibility it stalls are not related to global warming to rather simply to the location of high pressure systems north of the storm preventing it from turning northward.
The size of the storm could be argued to be greater due to warming, but its a statistical discussion about averages over time, not one of any particular storm.
What drives storms? Temperature differences.
This is nonsense. Hurricanes are not driven by temperature differences between the tropics and temperate regions. They are driven by vertical differences in temperature and pressure.
Warm seas cause warm humid air near the surface. Warm air is lighter, and high humidity makes it lighter still. So it rises, creating a low pressure region, and drawing in more surface winds that pick up heat and humidity as they move to the center of the storm. When the air in the center rises, it spreads out and cools, condensing the humidity that falls as rain. The cooler dryer air then descends on the edge of the storm.
Warmer seas cause stronger storms. Cooler water weakens the storm as it travels north, the opposite of what you are claiming.
If the oceans were uniformly warm, would we still have hurricanes? Yes, and they would be stronger, bigger, and last longer.
Shill group here, social-conservative morons
https://en.wikipedia.org/wiki/...
That's just an opinion piece, not a statement from Princeton itself. You DO know that, despite your Faux News Echo Chamber belief that only liberals get in to college because of the "libertardian take over" of education, there ARE conservatives go to college.
You are correct that hurricanes are not driven by the release of baroclinic instability and form in environments that are somewhat close to equivalent barotropic. Hurricanes are driven by latent heat release in the deep moist convection in the core, especially the eyewall storms. Air spirals in near the surface, ascends in the deep moist convection while releasing latent heat, and spirals outward in an anticyclone aloft. Hurricanes are warm core storms meaning that there is low pressure at the surface and high pressure aloft. You can see this in satellite images as the cirrus outflow aloft rotates anticyclonically, opposite of the storms in the rain bands and the inner core. I use the term "deep moist convection" rather than "thunderstorms" because there just isn't a lot of lightning in the inner core of tropical cyclones. However, lightning in the inner core can be associated with rapid intensification.
When the storm is over warmer water, the low-level inflow will be warmer and moister, resulting in more instability and stronger deep moist convection. The persistent release of latent heat causes high pressure aloft, which evacuates mass from the top of the storm in the outflow. The result of removing the mass aloft is that the pressure falls at lower levels including the surface. Vertical wind shear spreads the energy from latent heat release over a wider area, decreasing the strength of the upper-level anticyclone and causes less outflow at the top of the storm.
The horizontal component of Coriolis, or planetary vorticity, is weaker in the tropics and is zero at the equator, Persistent vertical motion in the deep convection stretches the planetary vorticity and causes hurricanes to spin. The same thing happens in persistent mid-latitude thunderstorms, which can start to spin. The result is called a mesoscale convective vortex. The process in mid-laittude storms is quicker in part because the horizontal component of Coriolis is stronger, but more because the vertical motion in those storms is stronger, resulting in more rapid stretching of planetary vorticity.
While the temperature difference between the tropics and poles does not significantly contribute to hurricane formation, it certainly could affect tropical cyclone behavior. Stronger temperature gradients in the lower and middle troposphere result in larger pressure differences aloft, which drives stronger upper-level winds. Weaker winds in the upper troposphere should generally result in tropical cyclones that move slower.
There is a difference between something "causing a storm" and "making storms more severe." There are few people if any saying climate change drives or causes new storms that wouldn't have occurred otherwise. But it's pretty obvious, and has been discussed for a long time now, that global warming means more heat and therefore more water and more energy in the atmosphere, which make storms more severe.
Cat 3s and less are minor for Florida. I listed 4, 5. Pattern, don't live in Florida just after WW2. Pattern is LESS powerful hurricanes as time goes on. So you provide a link that shows the OPPOSITE of what you claim it does.
If you AGW bullshit people told the truth, AGW would go away. Of course you have to lie, because the truth shows there isn't a problem. The only problem is your credibility.
Cat 5s
1935 - "Labor Day"
1992 - Andrew
That's it
Cat 4s
2017 - Irma
2004 - Charlie
1960 - Donna
1950 - King
1949 - Unnamed
1948 - Unnamed
1947 - Unnamed
I'm trying to figure this out....they're saying that global warming is going to cause this large storm to stall and dump rain?
I mean, it is moving about 15mph or so now, and is forecast to slow to like 3-7mph once it makes landfall....and somehow this slowdown is caused by global warming?
I mean, that is the reason they're worried about rain fall flooding.....
The effect of global warming in the Arctic is much greater than in the tropics (see Arctic amplification). This reduces the temperature differences going south to north which is one of the major drivers of wind. So the wind has slowed down which slows down the movement of weather phenomena embedded in the wind.
This study shows hurricanes have NOT increased in size (contrary to the title): https://www.wunderground.com/c...
"Tropical cyclone size does not appear to have changed significantly over the past 35 years."
Graph (it's a flat line): https://s.w-x.co/wu/storm-size...
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
Ok, here are a couple of non-Wikipedia sources on Arctic amplification:
Arctic amplification dominated by temperature feedbacks in contemporary climate models
Processes and impacts of Arctic amplification: A research synthesis
So it's actually a below-average hurricane season, but the media is taking advantage of the lone major hurricane heading towards the U.S. to push stories about how storms are getting worse. It's pretty naked confirmation bias.
It's not just size, it's also speed. Slowly moving over cities, dropping tons of rain.
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