Naked Science Forum
Life Sciences => The Environment => Topic started by: JoeBrown on 27/11/2016 15:09:28
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I've become overly concerned with the polar ice caps. Doesn't help that 2016 has seen record weather and record low ice in both Artic as well as Antartic regions.
Knowing a tropical cyclone/storm is a heat pump, the largest on Earth. Because so much heat is disbursed into the atmosphere, each storm probably has an effect on polar regions.
Googling for correlations has been fruitless. The data are complicated and connections likely minor at best. Difficult to draw without a lot of analysis. Am I barking up the wrong tree.
Would it be useful to identify correlations?
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The cyclone depends on a difference between cold, dry polar air and warm, wet tropical air. The warmer and wetter the polar air becomes, the less intense the cyclones. However the warmer and wetter the tropical air, the more intense the cyclones become. So the question becomes which area has gained the more heat energy over recent history, and I think on balance it is the polar egion.
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Polar regions are more sensitive to global warming than that rest of the globe.
While studying the Antartic area ice, sudden drops are difficult to ignore. I started wondering if they're coupled with tropical cyclones. Briefly looked at methods to correlate them, but can't justify analysis. Tho I would like to know.
https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/sea-ice-extent-area/grf/uh-amsr2-ant-area-overview.png
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Depends on what you mean by the journalese "more sensitive to.."
Obviously if the snowline retreats you will have a significant change in vegetation, insolation, and everything else, for a very small temperature change, whereas a desert is a desert and a tropical forest is a tropical forest, over quite a wide range of temperatures. But you need a lot of heat to move the snowline because you have to melt the snow (80 cal/gram) before the temperature can rise above 0 deg C, so whilst the ecology may be very sensitive to temperature changes, it is very insensitive to heat input!
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I meant the polar regions reflect warming more than the rest of the planet.
"more sensitive to.."
Best I can surmise the polar regions are one month off schedule.
The Artic is ~ 1 month behind average annual ice formation.
conversely
The Antartic is ~ 1 month ahead of annual ice retreat.
I don't know where antartic current and average temp, but according to http://ocean.dmi.dk/arctic/meant80n.uk.php it's warmer than usual in the artic.
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The energy for a cyclone is driven by local solar energy and water. When you vaporize liquid water, into water vapor, there is about a 1700 times expansion in volume. Therefore, the tropical sun, evaporating surface water into the atmosphere, adds partial pressure into the atmosphere as water vapor. This increases atmospheric pressure.
Low pressure systems appear when the water vapor is returning back to liquid, causing a local 1700 times reduction in the water vapor volume. This lose of water partial pressure, from the atmosphere, pulls a vacuum, causing the local pressure to lower. Low pressure systems usually have clouds and rain, both of which reflect the lowering of the partial pressure of the water in the atmosphere.
In terms of a cyclone, warm moisture laden air rises into the atmosphere, where is starts to cool and condense. The result is a pressure drop occurring above the forming tropical storm. This acts like a vacuum, which speeds up the uplift of even more warm moist air. The air goes higher and higher driven by the moving condensation vacuum. The loss of local partial pressure, pulls air into the tropical storm from all directions, which become part of its wind and may even become a vortex, which can feed even more moist air upwards to balance the vacuum. The pressure of cyclones gets very low to reflect the large volumes of water that is condensing and removing partial pressure.
One wild card is the heat of vaporization of water. When the sun evaporates the water, the sun need to add energy equal to the heat of vaporization for the water to enter the atmosphere. Water has an unusually high heat of vaporization compared to all materials. When the clouds form rain, this solar based heat of vaporization energy is released, within a more confined volume of space. Once a cyclone forms, the deduction of volume in the water vapor, 1700 to 1, not only pulls a vacuum, but it also releases lot of heat of vaporization. Since there is a net conversion back to liquid water; heavy rain, the excess energy is expressed in other ways. It become part of the fuel for the engine.
All and all cyclones don't add too much energy to the atmosphere, if we average over the entire cycle of the cyclone. There is a lot of solar energy in play, via the water, but it is transformed locally, into vacuum, kinetic energy and heat of vaporization. These will not show up as too much temperature rise, since much of the energy is being expressed in other ways.
It is sort of like using gasoline to run a car. After we subtract the work, there is not as much heat from a gallon of gas left over. In fact, thunderstorms tend to cool the surface mixing the air in the upper and lower atmosphere bringing the heat out toward space.