Snow from a Nuclear Plant
I don't discuss climate change and anthropogenic global warming very often. For me, the science is settled; it's a done deal. The issue of global warming, like the problems associated with the ozone hole, DDT, leaded gasoline, or second-hand cigarette smoke, has many angles and complexities. Obviously, it stimulates many opinions. Whenever I discuss this issue, I always try my best to separate the science from policy.
There is common ground on which most scientists agree: Burning fossil fuels releases carbon dioxide (CO2) into the atmosphere; we burn a lot of fossil fuels, and atmospheric concentrations of CO2 are increasing. More importantly, there's strong consensus that human activity has changed the atmospheric composition of carbon dioxide.
Even the most hardened scientists who remain skeptics about global warming agree that CO2 has a warming effect. For the record, the warming effects from CO2 dates back more than a century (military research conducted during, and just after, World War II got the physics exactly right). Attributing the recent warming to human activity is more of a hurdle when it comes to scientific consensus, but even most of the hardened skeptics and, essentially all of the mainline climate scientists, agree that warming has occurred over the last century and that human activity was expected to cause warming.
The 0043Z base reflectivity from KPBZ (Pittsburgh). At the time, the radar was in clear-air mode. Larger image. Courtesy of NCDC and NOAA.
In addition to anthropogenic climate change, there are palpable examples that illustrate how human activity impacts our atmosphere. The examples I have in mind are perceptible changes in daily weather. Just the other day (the late afternoon and early evening of January 22), the effluent from a nuclear power plant located in Shippingport, PA (near Pittsburgh in western Pennsylvania) caused a plume of snow that spread eastward with westerly winds in the lower half of the troposphere. I'll add here that there's also a coal power plant nearby that might have also contributed to the snow plume.
To see the radar footprint of the snow, check out the 0043Z image of base reflectivity (above; larger image) from KPBZ (Pittsburgh). I note that the radar was in clear-air mode (and not precipitation mode) at the time, allowing the radar to better detect and display snow.
For a more complete view, check out the animated gif (radar loop) from 23Z to 01Z (6 P.M. to 8 P.M.). This animated gif comes courtesy of the National Weather Service at Pittsburgh.
To get a better sense for the eastward evolution of the snow plume, check out the vertical profile of westerly winds on the 00Z GDAS skew-T at Wexford, PA (see Wexford's 00Z GDAS skew-T below; refer to my previous blog about skew-Ts). I chose Wexford because the radar loops indicate that the plume moved over this town (revisit the animated gif from 23Z to 01Z). In case you're wondering, GDAS is the Global Data Assimilation System used by the GFS model for initial conditions. Specifically, GDAS uses variational and statistical methods to blend all types of weather observations into the model background (usually based in the previous run's forecast cycle). In this way, the effects of weather observations can propagate forward in time.
The 00Z GDAS temperature and dew-point soundings at Wexford, Pennsylvania, on January 23, 2013 (7 P.M. EST on January 22).
At any rate, note that the precipitating layer over Wexford at 00Z (7 P.M. local time), which spanned from roughly 900 mb to 800 mb. I can infer precipitation was present because the troposphere was saturated in this layer. Also note the stable layer just above 800 mb (roughly isothermal), which was likely caused by subsidence above 800 mb (check out the 00Z Rapid Refresh model analysis of vertical motion, expressed in microbars per second; positive values indicate downward motion).
Any way you slice it, that's a relatively shallow precipitating layer. Although it snowed for approximately four to six hours hours, accumulations were only about one inch (yet there were reports that the snow caused traffic to back up on I-79 near Wexford). For the record, visibility under this plume was less than a one-half mile. In general, snow was light, but that doesn't diminish my point that human activity has perceptible impacts on the atmosphere.
The precipitating cloud associated with the plume of snow was a mixing cloud (the same cloud you observe when you see "your breath" on a cold day. In this case, hot water vapor in the effluent belching from the cooling towers of the nuclear plant (and possibly the nearby coal power plant) mixed with Arctic air (cold and dry), producing a mixing cloud. In turn, ice nuclei in the effluent served as sites for ice crystals to grow, setting the stage for an anthropogenic snow band. Yes, human activity has perceptible impacts on the atmosphere.
For the record, ice nuclei in ordinary clouds are not as ubiquitous as condensation nuclei. In this case, it's difficult to say exactly what kind of ice nuclei were present in the effluent from the power plants.
I should also point out that the National Weather Service referred to the effluent as "steam blowing from the stacks" on their Facebook page. For the record, steam is invisible water vapor at the boiling point. Indeed, almost everyone uses the word, "steam," incorrectly. I don't have any problem with a "steam cloud," but steam is invisible, by definition.
No big deal, but I thought I'd mention it. You know me.