Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror

Comment: Re:A couple of points : (Score 5, Informative) 232

by mps01060 (#41785243) Attached to: Slashdot Asks: Are You Preparing For Hurricane Sandy?
A couple of points:

1. Precipitation:
You have to consider that the land types are different for the northeast states compared to southeast states such as Florida. Florida has soil in which the rain drains out of much quicker. In addition, engineering designs are different for states that generally get less rain than the southern states. The HDSC calculates precipitation Recurrence Intervals for engineering design purposes. For example, Florida sees a mean annual maximum precipitation of about 5 inches in 24 hours compared to 2.5 inches in 24 hours in the northeast. This discrepancy is much larger when you look at recurrance intervals of >10 years (9 compared to 5 inches). This event has the potential to drop 100 year rainfall on the northeastern states. It will last a few days, but MOST of the rain will fall in one day.

2. Wind:
This will likely transition into an extratropical cyclone. extratropical (mid-latitude) storms have weaker winds than hurricanes, but are over a much larger area. Most hurricanes have severe wind damage only a few miles from the center in the eye-wall. Tropical storm strength winds extend out further, but even those don't usually extend out far in most storms (obviously there are exceptions such as Hurricane Ike). An extratropical cyclone's winds will cause moderate damage over a very large area. The other thing to consider are trees. Trees in the north are much less resistant to the wind, especially since most still have their leaves this time of the year. The winds in this storm won't be as deadly as a hurricane's, but will be a HUGE issue for damage and power outages.

Storm surge:
This is a page with estimated storm surge. This storm will also stick around for a while, so it will be able to pile more and more water up against the shore, as well as have a chance to coincide with astronomical high tides. There are many places in NYC that will flood (although they will be properly evacuated).

3. People
If the center hits around southern New Jersey, this storm will directly affect Washington DC, Baltimore, Philadelphia, NYC, etc. This is a very large amount of people to worry about. These people are used to Nor' Easters but this should be much stronger than a typical Nor' Easter.

I do understand why you think this is being over-hyped, especially when you compare it to the smaller but much more powerful hurricanes that strike the south. Overall, I don't expect this storm to cause many deaths; I think the people will generally be prepared. I do see this storm causing a lot of damage and long-lasting power outages. When you have these affects over such a large area, it could take time to get back to business as normal. Lastly, you should look for more information on Irene because it was very damaging, especially with the flooding in NY and VT, where both the infrastructure and the land type is not used to that kind of rain.

Comment: Re:Another thing to worry about... (Score 1) 269

by mps01060 (#41286315) Attached to: Mt. Fuji May Be Close To Erupting
You are correct in most of what you are saying, but don't ignore the fact that Icelandic volcanoes are on a divergent boundary, rather than a convergent boundary (subduction zone). Volcanoes near subduction zones are much more explosive because they have gasses like water vapor mixed into their magmas/lavas.

Comment: Re:Didn't Roland Emmerich make this movie (Score 1) 259

by mps01060 (#37616444) Attached to: Severe Arctic Ozone Loss
I know I'm really reaching back here, but I remember that movie driving me nuts during the "freezing" scenes. If air from the upper troposphere/lower stratosphere descended to the surface, it would descend at the dry adiabatic lapse rate, which is ~10 degrees C per km of height. The top of the troposphere is ~10 km above the surface and the temperature is around -60degrees C. This means that air that descended from there (assuming its dry) would compress and warm adiabatically to +40 degrees C by the time it reached the surface. People would be suffering from heat stroke rather than freezing.

Comment: Little more detail (Score 5, Informative) 259

by mps01060 (#37611872) Attached to: Severe Arctic Ozone Loss
These aren't traditional clouds that you see in the troposphere (lowest layer of the atmosphere). To get an ozone hole, you need VERY cold temperatures. This happens after during polar night when there is no sunlight for about half the year. The stratosphere is so cold that it can form ice crystals that contain nitric acid. These crystals act as surfaces where ozone destruction takes place. Once the sun rises at the pole (March equinox for the northern hemisphere), the UV light "splits" compounds like CFCs into reactive materials such as Chlorine. The ozone destruction reaction still will not work efficiently without the initial nitric acid/ice crystal surfaces. This is why we don't often see this happening in the Arctic, while the Antarctic shows this signal annually.

http://www.noaa.gov/features/02_monitoring/arctic_thinning.html

The "coldness" of the pole is related to the strength of the winds (polar vortex) around the pole in the atmosphere. The south pole generally has strong winds circling it, which works to cut off the south pole's atmosphere from the rest of the world, especially during the southern hemisphere winter. Part of the reason for a stronger vortex is due to ocean surrounding the south pole on all sides, with land masses far away. In addition, the southern hemisphere in general has more ocean compared to land than the northern hemisphere.

In the northern hemisphere, the polar vortex generally has more waves or pertubations in the polar vortex, which help to mix in air from lower latitudes. Some of this is caused by planetary waves that propagate vertically in the atmosphere. These planetary waves are formed generally due to land masses and mountains affecting the atmospheric flow (not this simple but this is the general idea). Generally, the factor that causes the difference in the north and south polar vortices is land mass.

Now relating this all to climate is a bit tricky. It has been seen that as the troposphere warms (lowest layer of the atmosphere), the stratosphere cools. This has been seen in observations in the last 30-50 years (you may argue that 50 years might not be enough to define a long-term trend). The reason for this cooling is basically radiative balance (though I'm oversimplifying it here). If the troposphere warms due to increased greenhouse gasses, then the atmosphere above must cool above it. There cannot be more heat coming in than is leaving the Earth. A good analog to this is Venus. Venus has huge concentrations of greenhouse gasses. We know its surface is very hot (over 400 degrees C), while its upper atmosphere is much cooler than Earth's (gets down below -110 degrees C, compared to about -80 C on Earth).

The tough part is separating the stratospheric cooling due to greenhouse gasses and ozone destruction from CFCs (although we may know this answer once all the CFCs are out of the atmosphere in the future). Increased greenhouse gasses will warm the troposphere and cool the stratosphere. This will lead to more polar stratospheric clouds, leading to more reactions sites for ozone destruction. More ozone destruction means less UV light is absorbed by ozone in the stratosphere. Less UV absorption means a cooler stratosphere which further intensifies the problem.

Transportation

Dutch Town Lays Air-Purifying Concrete 295

Posted by CmdrTaco
from the i-hate-august-news-cycles dept.
eldavojohn writes "In an effort to combat air pollution, a Dutch town has paved some of its streets with air-purifying concrete. It contains a titanium dioxide-based additive that utilizes sunlight to turn car exhaust into harmless nitrates. It was shown to do this in a lab and now the scientists are interested in just how much this will affect the air quality around the road. They will sample the air quality by a normal road and by this newly paved one."

Don't sweat it -- it's only ones and zeros. -- P. Skelly

Working...