Where Have the Hurricanes Gone?

[Berzerker]

I dont buy this argument global warming results in more storms and strongers storms, it seems logical the worst storms and most activity would occur during ice advances because there is a greater contrast between the higher latitudes and the equatorial region. We have 2 tornado seasons but the spring season is by far the worst. Thats because the north is still producing cold dry air and sending it down the Rockies to collide with warm moist air from the gulf. The Fall season follows the summer heat warming even the higher latitudes and the north doesn't produce the same air mass and the conflict with the warmer moist air from the Gulf is much less severe. If hurricanes distribute heat away from the equatorial latitudes toward the poles, the transition is less violent when the poles are a little warmer. After all, the "greenhouse effect" assumes a warmer Earth which also means a more uniformly warmer Earth.

[chequita guevara]

Originally posted by DinoDoc
Don't jinx it.

[Odin]

Originally posted by Berzerker
I dont buy this argument global warming results in more storms and strongers storms, it seems logical the worst storms and most activity would occur during ice advances because there is a greater contrast between the higher latitudes and the equatorial region.

Temperature contrasts don't have anything to do with hurricane formation. Temperature contrasts are the fuel for temperate weather systems, not tropical ones. Hurricanes are fueled by the energy released by the condensation of water vapor.

From Wiki:

Structurally, a tropical cyclone is a large, rotating system of clouds, wind, and thunderstorms. Its primary energy source is the release of the heat of condensation from water vapor condensing at high altitudes, the heat ultimately derived from the sun. Therefore, a tropical cyclone can be thought of as a giant vertical heat engine supported by mechanics driven by physical forces such as the rotation and gravity of the earth.[1] In another way, tropical cyclones could be viewed as a special type of Mesoscale Convective Complex, which continues to develop over a vast source of relative warmth and moisture. Condensation leads to higher wind speeds, as a tiny fraction of the released energy is converted into mechanical energy;[2] the faster winds and lower pressure associated with them in turn cause increased surface evaporation and thus even more condensation. Much of the released energy drives updrafts that increase the height of the storm clouds, speeding up condensation.[3] This gives rise to factors that provide the system with enough energy to be self-sufficient and cause a positive feedback loop where it can draw more energy as long as the source of heat, warm water, remains. Factors such as a continued lack of equilibrium in air mass distribution would also give supporting energy to the cyclone. The rotation of the earth causes the system to spin, an effect known as the Coriolis effect, giving it a cyclonic characteristic and affecting the trajectory of the storm.

The factors to form a tropical cyclone include a pre-existing weather disturbance, warm tropical oceans, moisture, and relatively light winds aloft. If the right conditions persist and allow it to create a feedback loop by maximizing the energy intake possible, for example, such as high winds to increase the rate of evaporation, they can combine to produce the violent winds, incredible waves, torrential rains, and floods associated with this phenomenon.

Condensation as a driving force is what primarily distinguishes tropical cyclones from other meteorological phenomena.[4] Because this is strongest in a tropical climate, this defines the initial domain of the tropical cyclone. By contrast, mid-latitude cyclones draw their energy mostly from pre-existing horizontal temperature gradients in the atmosphere.[4] To continue to drive its heat engine, a tropical cyclone must remain over warm water, which provides the needed atmospheric moisture. The evaporation of this moisture is accelerated by the high winds and reduced atmospheric pressure in the storm, resulting in a positive feedback loop. As a result, when a tropical cyclone passes over land, its strength diminishes rapidly.[5]

The passage of a tropical cyclone over the ocean can cause the upper ocean to cool substantially, which can influence subsequent cyclone development. Tropical cyclones cool the ocean by acting like "heat engines" that transfer heat from the ocean surface to the atmosphere through evaporation. Cooling is also caused by upwelling of cold water from below. Additional cooling may come from cold water from raindrops that remain on the ocean surface for a time. Cloud cover may also play a role in cooling the ocean by shielding the ocean surface from direct sunlight before and slightly after the storm passage. All these effects can combine to produce a dramatic drop in sea surface temperature over a large area in just a few days.[6]

Scientists at the National Center for Atmospheric Research estimate that a tropical cyclone releases heat energy at the rate of 50 to 200 trillion joules per day.[3] For comparison, this rate of energy release is equivalent to exploding a 10-megaton nuclear bomb every 20 minutes[7] or 200 times the world-wide electrical generating capacity per day.[3]

While the most obvious motion of clouds is toward the center, tropical cyclones also develop an upper-level (high-altitude) outward flow of clouds. These originate from air that has released its moisture and is expelled at high altitude through the "chimney" of the storm engine.[1] This outflow produces high, thin cirrus clouds that spiral away from the center. The high cirrus clouds may be the first signs of an approaching tropical cyclone.[8]

Berz is pwned one again.

[dannubis]

stop making sense !

i want to use my USV that burns 25 liters per 100 km !

[Solly]

Originally posted by Odin
North Atlantic Hurricanes != All tropical cyclones

They seemed to last year.

[Berzerker]

Berz is pwned one again.

Funny, you switched the topic from hurricanes to tropical cyclones in order to "pwn" me? From your article:

By contrast, mid-latitude cyclones draw their energy mostly from pre-existing horizontal temperature gradients in the atmosphere.

You pwned yourself, the contrast between these horizontal temperature gradients is less severe when the higher latiitudes are warmer. Your article supports what I said. How'd you miss
that?

[Berzerker]

Temperature contrasts don't have anything to do with hurricane formation.

mid-latitude cyclones draw their energy mostly from pre-existing horizontal temperature gradients in the atmosphere.

just had to post that self-pwnage again

[RGBVideo]

Originally posted by Berzerker
it seems logical the worst storms and most activity would occur during ice advances because there is a greater contrast between the higher latitudes and the equatorial region. We have 2 tornado seasons but the spring season is by far the worst. Thats because the north is still producing cold dry air and sending it down the Rockies to collide with warm moist air from the gulf. The Fall season follows the summer heat warming even the higher latitudes and the north doesn't produce the same air mass and the conflict with the warmer moist air from the Gulf is much less severe. If hurricanes distribute heat away from the equatorial latitudes toward the poles, the transition is less violent when the poles are a little warmer. After all, the "greenhouse effect" assumes a warmer Earth which also means a more uniformly warmer Earth.

[RGBVideo]

Flubber wrote:
Normal yearly variation I expect.

Funny, last year it was Global Warming.

not according to Flubber, and not according to me

so it looks like this is a red herring

[Berzerker]

I was educated in liberal California, and dont look now but I'll bet Kansas' schools are kicking their ass. I've seen some really stupid rebuttals but citing a geographic location and the actions of some politicians as your proof is about the dumbest yet. Nah, thats an overstatement...

so it looks like this is a red herring

http://earthobservatory.nasa.gov/Library/Hurricanes/

Hurricane Formation and Decay
Hurricanes form over tropical waters (between 8° and 20° latitude) in areas of high humidity, light winds, and warm sea surface temperatures (typically 26.5°C [80°F] or greater). These conditions usually prevail in the summer and early fall months of the tropical North Atlantic and North Pacific Oceans and for this reason, hurricane "season" in the northern hemisphere runs from June through November.

Even when the conditions are ripe for hurricane formation at the surface, the storm may not form if the atmospheric conditions aloft (5-10 km above the surface) are not favorable. For example, around the area of 20° latitude, the air aloft is often sinking, due to the presence of the sub-tropical high—a semi-permanent high pressure system in the subtropical regions that facilitates sinking air motions (subsidence). The sinking air warms and creates a temperature inversion (an extremely stable air layer in which temperature increases with altitude, the inverse of the usual temperature profile in the lower atmosphere) known as the trade wind inversion. This warm layer is very stable, making it difficult for air currents to rise and form thunderstorms and (eventually) hurricanes. In addition, strong upper-level winds tend to decapitate developing thunderstorms by dispersing the latent heat and cutting off the storm’s source of fuel.

Notice how its a northern warm trough of air that needs to weaken for hurricanes to form or move northward? Thats a temperature gradient forming when northern air masses are alot cooler than tropical air masses. when they're closer in temperature, the gradient is less and the warm stable air north of the storm track inhibits hurricane growth and strength.

And one more thing Odin, you say temperature gradients have nothing to do with hurricanes? Its a temperature gradient within the tropical disturbance that allows hurricanes to form.

[Odin]

Originally posted by Berzerker




just had to post that self-pwnage again

Hurricanes are LOW lattitude systems, you moron.

[Kuciwalker]

Odin, I have to say you're the moron for caring so much about this that you casually toss around insults in your first post.

Get a grip. Better, get a girl.

[Lorizael]

Get a grip on a girl!

[Kuciwalker]

Lorizael gets it

[Berzerker]

Hurricanes are LOW lattitude systems, you moron.

But they move into mid latitudes...where we just happen to find the USA - hence the subject of this thread. And you will notice that a strengthening/weakening temperature gradient around the 20th latitude is related to the number and strength of hurricanes reaching the USA. And since some hurricanes form closer to that latitude, some wont form because the needed temperature gradient is lessened by the inversion. If the inversion weakens, a temperature gradient strengthens and the storm gains fuel instead of losing it. Btw, you ignored the fact a temperature gradient is needed for a hurricane to form in the first place, much less travel northward.

"Even when the conditions are ripe for hurricane formation at the surface, the storm may not form if the atmospheric conditions aloft (5-10 km above the surface) are not favorable. For example, around the area of 20° latitude, the air aloft is often sinking, due to the presence of the sub-tropical high—a semi-permanent high pressure system in the subtropical regions that facilitates sinking air motions (subsidence). The sinking air warms and creates a temperature inversion (an extremely stable air layer in which temperature increases with altitude, the inverse of the usual temperature profile in the lower atmosphere) known as the trade wind inversion. This warm layer is very stable, making it difficult for air currents to rise and form thunderstorms and (eventually) hurricanes."

Why would a warm layer inhibit hurricane activity? Because hurricanes develop as moist warm air rises within the disturbance or depression. But if the layers above the forming hurricane are already warm, and the temperature gradient is slight or modest, the hurricane doesn't form or breaks up.