Ask Analytic - Hows the Weather

3. Why Does this Book Express Thermal Comfort as PMV Index Instead of the Popular Heat Index?
In "How's The Weather?," the PMV Index (the centerpiece of the book, see Chapter 4 and Chapter 5) is favored by the author over the Heat Index for several reasons, listed in decreasing order of significance below:

(a) The PMV Index (1970), is progenitor of the Heat Index (1978), and experimental data for the former imply mathematical validity only within the PMV range of "-3.0," and "+3.0."

Inappropriately, the Heat Index table, which is based on the same mathematics, displays frequent extrapolations beyond the counterpart PMV "+3.0" limit (refer to chart in "1." above)

(b) Whereas the PMV Index yields the useful concept of "Percentage of People Dissatisfied" (PPD - see Chapter 4), the Heat Index ignores this bonus information.

(c) Whereas the PMV Index assumes a sedentary (sitting) condition, the Heat Index is based on walking at the rate of 3.14 miles/hour.

(d) Finally, admittedly a matter of personal opinion, the concise and symmetrical PMV Index, which ranges from "-3.0," ... "0," ... "3.0," may be considered by some to be more comprehensible and intuitive than the Heat Index, displayed below:

"Any value less than 80°F is comfortable."
"Any value greater than 90°F is considered extreme."
"Any value greater than 100°F is considered hazardous."
"Any value greater than 110°F is considered dangerous."

4. What Is the Impact of Global Warming on Historical Climate Data?
Probably little or none. The often reported examples of global warming simply do not withstand scientific scrutiny.

An overwhelming scientific consensus disagrees with the headline seeking news media about the existence of global warming, either anthropogenic or otherwise.

(For general commentary about global warming, see the modest collection of citations on this Web site, especially (1) by the SEPP organization (see S. Fred Singer, below), (2) by the Oregon Institute of Science and Medicine, and (3) arguments by Rep. Dana Rohrabacher.

(a) Global warming is usually confused by news media with the urban heat island effect (UHI).

Simply stated, the population-based UHI effect is due to (1) replace-ment of native vegetation by concrete and asphalt together with (2) heat emissions from industry, buildings and automobiles.

Important distinctions between global warming and UHI effects are decribed in Chapter 14 (pdf) of this book.

(b) Scientific testimonies which argue against global warming are commonly ignored by the news media and most politicians.

For example, testimony (pdf) by Professor S. Fred Singer, astrophysicist and founder/president of the Science & Environmental Policy Project (SEPP), which was presented before the Senate Committee on Commerce, Science, and Transportation, was apparently ignored by chairman Senator John McCain.

Testimony (pdf) to the same committee by John Christy, Professor of Atmospheric Science and Director of the Earth System Science Center at the University of Alabama in Huntsville, contains the following noteworthy paragraph:
Computer models indicate that since the 1890's we in North Alabama should have experienced a warming of about 2 F (1C). The truth is that we have actually experienced a cooling of over 2 F (1C).

(c) Temperature trend line studies of U.S. small-population cities (which are expected to exhibit only minimal urban heat island effects) show no persuasive evidence of regional warming during the past 55 years.

On the contrary, there is both statistical and inferential support for regional cooling within the small population cities (especially conspicuous for Camilla, GA, which represents a city with unusually small population from among those studied).

Moreover, the most recent 24-year time segment for Camilla, GA, exhibits the highest rate of cooling within the 55-year time period.