Thursday, June 30, 2011

A HEPA-type air-filtration system for ~$25.

I'm just getting over my allergies -- that were causing me troubles for much of the springtime. It was with this in mind that it made me very happy to see a story about building a cheap air purification system.

To avoid indoor allergens, many doctors recommend using an air purifier with a High Efficiency Particulate Air (HEPA) filter. The cost of these machines can run from $75 up to $800 for high-end systems. For those who are looking for a cheaper alternative for high-use rooms such as the bedroom, Terrell offers a do-it-yourself solution at a fraction of the cost. “This is a filtration system that you can put together with items from your local hardware store for $25 to $30 and use in your home to cut indoor allergens by about 90 percent,” says Terrell.

h/t: Inhabitat

Tuesday, June 28, 2011

Increasing number of strong hurricanes

I'm reading Changing Planet, Changing Health, and I came across a mention of increased number of more intense storms:
Studies over the last five years have shown that hurricanes are getting stronger. In a 2005 paper in Nature, meteorologist Kerry Emanuel of the Massachusetts Institute of Technology described a new measure, the power dissipation index, that captures the amount of energy that flows through a hurricane over its lifetime. ... The same year, Peter Webster's team at Georgia Tech University reported in Science that while the total number of tropical cyclones per year stayed roughly constant worldwide, the strongest storms -- category 4 and 5 storms ... -- nearly doubled over thirty-five years.
Then, the figure from the Webster et al paper was presented. However, the data that was included was from 1970-2004. Looking at that, I realized that there was enough of a time interval since the publication of the paper to extend it by another lustrum. While waiting for students, I decided to track down the data for the period of 2005-2009. Using the various hurricane records from Wikipedia (and roughly estimating the lustral hurricane values published by Webster et al), I was able to come up with the following (expanded) graphic:

As you can see, the most recent lustrum was characterized by a slight decline in Category 1 storms, a serious decline in Category 2 & 3 hurricanes, and a very small increase in the number of Category 4 &5 hurricanes worldwide.

Recalculating to collapse the categories into decades, we can look at how many more (or fewer) storms were occurring worldwide during the 2000s relative to the 1970s. From the data, we find that there were 25% fewer Category 1 storms, 10% fewer Category 2 &3 storms, and 91% more Category 4 &5 storms worldwide in the 2000s compared to the 1970s! To quote further from the book about the significance of this trend:
Top hurricane researchers do agree that as the globe warms, hurricanes will intensify, though the total number of hurricanes will remain relatively constant, or perhaps even drop.

While I don't have worldwide data on this, it seems to track with the trend in the record-high-temp-to-record-low-temp ratio over the continental United States over the same period of time does indicate continued warming:

The trends of an increasing number of high power storms corresponds to the expectation of increased magnitudes of storms caused by increasing global temperatures, and the high-record-temperatures across the continental United States corresponds with expectations of larger-scale warming trends that are being seen throughout the world.

What does all this mean? Well:
In 2010, Science published a study by Morris Bender, Tom Knutson, and Robert Tuleya ... [that] concluded from modeling studies that category 4 and category 5 hurricanes will double in frequency in the Atlantic this century because of ocean warming.
And with an increased number of hurricanes globally comes increased incidence of disease outbreaks, famine, and price spikes in commodities (e.g., food, fuel) increasing the likelihood of war (or at least some sort of punitive action by one group of people against another; state-sanctioned or not).

ADDENDUM: The number of storms in the 1975-1979 and the 2005-2009 lustra were both well below the lustral average of ~240 storms/lustrum; '75-'79 had ~206 storms, and the '05-'09 had 217. All the other lustra experience between ~232 and ~270 storms.

ADDENDUM: Webster et al use the term "pentad" to refer to a period of five years, while I prefer the use of the term "lustrum". Looking at the Wikipedia entry for "lustrum", one finds that "pentad" is synonymous, as is "quinquennium." However, "pentad" is a general term that means a group of five things, while "lustrum" specifically means a period of five years. Of course, "quinquennium" also means a period of five years. However, it's a lot more difficult to spell than either "lustrum" or "pentad".

ADDENDUM (06/30/11): I tried to extend the graph to earlier lustra, but soon realized that this might be difficult, since gaps in the data exist on Wikipedia. (The gaps might not be problematic ... if I actually wanted to wade through all the raw data.) Therefore, since I don't want to commit too much more time on this, I'll be leaving the analysis (as much as it's an analysis) as is.

Tuesday, June 14, 2011

Hurricane Categories: Why are we only using five categories?

In reading books and articles written about a future in which we have to adapt to a certain amount of climate change, one is struck by the consistency of using New Orleans and Hurricane Katrina as an example that illustrates many of the social considerations that future planning must incorporate. This make sense, since we wouldn’t care about the effects of climate change if it were happening elsewhere (i.e., we don’t care about how the climate is or isn’t changing on the planet Xenu, nor how it is affecting what may be living there). This is analogous to the underlying meaning behind the question, “If a tree falls in the woods, and no one is there to hear it, does it make a sound?” (The question never made sense to me, because I grew up with the “strange” notion that sound is a byproduct of the motion of air, and so it doesn’t matter who may – or may not – be in proximity of any object that makes a sound; it will happen. Considering the implication of the question to be something more than a physical description didn’t dawn on me until my 20s.)

In the last days of August, 2005, the city of New Orleans was hit by the eleventh Atlantic hurricane, named Katrina. It had – prior to landfall – reached a “Category 5” condition, but by the time it made landfall, had diminished to “Category 3.” Still, due to several factors – the greatest of which were undoubtedly the catastrophic failure of the levees, the lack of a city-wide evacuation order, and the systematic loss of buffering wetlands and barrier islands – the city suffered widespread flooding, and the death toll shocked the nation and the world. Many of us know these basic facts about Hurricane Katrina; many of us know additional facts. However, my most recent reading of these facts piqued a question: “In a world that is warmer, how strong might the hurricanes get?” From that, as series of other questions, including, “Why is ‘Category 5’ the strongest category?” or, to put it in another way, “Why are there only five categories?”

Looking online, it is easy to discover the basic facts of the “Category” system (called the Saffir-Simpson Hurricane Scale, or SSHS for short): there are five enumerated categories, as well as additional classifications of “tropical depression” and “tropical storm” that below the “Category 1” hurricanes; that Category 1 hurricanes have wind speeds of 74-95mph, Category 2 of 96-110mph, Category 3 of 111-130mph, Category 4 of 131-155mph, and Category 5 of >155mph; and that the system is used by the US (other places may use other systems). Doing a query for the fastest wind speed ever recorded in a hurricane, I found that Hurricane Camille (1969) maxed out the meter at around 205mph; 50mph faster than the minimum for a Category 5 hurricane, which is a much greater interval difference than any other category. True, Hurricane Camille-strength equivalents do not often show up in recorded history, making them a statistical rarity, and it would therefore make sense that their consideration might not have been deemed “necessary” at the time when the SSHS was conceived in 1971 – even though it was derived after Camille.

As a side note, looking at the historic hurricane data from NOAA, there have been 77 weeks – in the corrected data record – during which there has been a hurricane with wind speeds at or exceeding 155mph, 48 weeks of which exceeded 160mph, 12 weeks of which exceeded 170mph, and 3 weeks of which exceeded 180mph. As of the writing of this entry, the NOAA site has records for 1949-2010 for the Eastern North Pacific and for 1851-2010, with possibly some years missing (i.e., check the website for the most up-to-date stuff). For example, I cannot find the data for Camille in the NOAA data that I used to get these hurricane wind speed frequencies. However, even looking at the historic hurricane record of the waters near the US, it is pretty clear that there have been times when the winds have been significantly stronger than 155mph. In these conditions, wouldn’t it be better to have other categories in order to compare and discuss differences between hurricanes?

Now back to my original train of thought.

If we are going to be approaching a world in which hurricanes will be stronger, then wouldn’t it be likely that Camille-class hurricanes will be more likely? If so, then why not extend the range into Category 6 and possibly beyond? I mean, just because one has not yet encountered such a hurricane doesn’t mean that one cannot set aside a classification for it. Helpfully, the Wikipedia page for the HHSH presents a formula for deriving the maximum wind speed for Categories 1 through 4 (remember that Category 5 has no stated maximum) as: 83x10^(c/15) mph, where c is the category number, rounding the final number to the nearest multiple of 5. (One thing to note is that if you plug in c=4, then you will get a value of 147.8mph, which, even when rounding to the nearest multiple of 5, will only get you 150mph, which is kind of screwy. In my calculations, I will use the calculated value of 150mph, instead.) The resulting Categories 1-7 are:

Category 1: <95mph
Category 2: 96-110mph
Category 3: 111-130mph
Category 4: 131-150mph
Category 5: 151-175mph
Category 6: 176-205mph
Category 7: 206-235mph

If we assume that Camille did, indeed, exceed the 205mph that was recorded before the measuring device broke, then it would place that hurricane just inside Category 7; two categories higher than what the current system can allow, and thus making it possible to show just how much stronger those winds were. Furthermore, using 150mph as the corrected break point between a Category 4 and Category 5 hurricane, this would mean that there were 114 weeks of hurricanes at or exceeding 150mph! (Recall, too, that some data are – at this point – missing from the historical analysis, so it is likely that the true number is larger.) Of these 114 weeks, 5 of them would be classified as Category 6, and – because of the incomplete data set – none exist in Category 7 (save anecdotally for Camille).

Being able to say that there had been at least one Category 7-hurricane as well as at least five weeks of Category 6-hurricanes presents a very different description of hurricane activity than saying that they are all Category 5s. Furthermore, with wind speeds of future hurricanes expected to increase due to increased sea temperatures, we may well need to start adding higher categories as a normal course of action.

UPDATE: Looking at Wikipedia, someone had also listed a Category 6 criticism, with a quote from a former NOAA hurricane center administrator and co-inventor of the SSHS that, "there is no reason for a Category 6 on the Saffir-Simpson Scale because it is designed to measure the potential damage of a hurricane to manmade structures. If the wind speed of the hurricane is above 155 mph (249 km/h), then the damage to a building will be 'serious no matter how well it's engineered'." However, this sounds like the wrong logic. Why not have a Category 6, 7, 8 or more, since the metric isn't potential damage to structures (which might be expressed as a percent), but is rather wind speed. The implication of a wind speed is that there will be concomitant structural damage, but wind speed is not a measure of structural damage. Furthermore, the presumption is that it is impossible to build a structure to withstand the occasional 155mph sustained wind. Once people build structures that can withstand 155mph of sustained wind, the whole premise of the "argumentation" falls apart, since now there's a structure that is well-enough engineered to withstand the high winds. Hey, granddad! Technology progresses! I know that you invented the SSHS, but don't hobble us with your generational thinking and personal biases!

UPDATE: The Taipei 101 tower is a 101-floor skyscraper that was designed to withstand sustained 136mph winds. The Gateway Arch in St. Louis is designed to flex 18 inches in sustained 150mph winds. Furthermore, according to one site, "Most steel buildings that are engineered to resist hurricane damage can withstand wind forces up to 170 mph." (This claim can be seen elsewhere on the interwebs.) Sorry, Bob, what were you saying about buildings not being able to withstand 155mph winds? Tell us again, using your incomplete and now falsified reasoning, as to why we don't need a Category 6?

Friday, June 10, 2011

Peak oil and what counts as a "big" find

Andrew Sullivan displays a graph of new discoveries of oil.

It's important to note that this is new oil discoveries using the MOST OPTIMISTIC estimates of the finds. Further, it's important to note that on top of these discoveries of oil, there is a world that is using increasing amounts of oil. (In other words, it's not just about your country's use of oil, but the world's use of oil.)

Unless companies, governments, and academics are all in on a secret cabal, we have reached peak oil, and we're on the downward slope, and it makes all the current discussions (in the US) about gas prices being too high (even though it is much lower in real and relative amounts than compared to any OECD country) absurd.

In a future world that is post-peak, one needs to learn how to find new sources of energy and learn how to diminish energy consumption. ... or create even more serious inequalities between rich and poor.