No, I’m not talking that kind of climate change. What I am going to talk about is the impact of consumer preferences with respect to tablet size, based on where you live.

The debate is whether consumers prefer tablets screens closer to 7 inches diagonally or 10 inches diagonally. Obviously Apple continues to dominate with a 4:3 aspect ratio tablet close to the high end of that range, whereas Samsung and Research In Motion have 16:9 aspect ratio 7-inch tablets in the market today.

The idea has grown on me that we may be facing a factor similar to that of determining the suitability of electric cars, and that’s the climate in which you live. Why?

Let’s start with the argument we often hear, in favor of smaller 7-inch tablets such as those offered by RIM and Samsung right now. Reviewers often state that they don’t take their Apple iPads outside their houses, other than perhaps to bring it on a trip to use primarily on flights.

I have never understood this argument, because I carry my iPad in my hand almost everywhere I go, probably 99% of the time. It is comfortable to hold, and is protected by the excellent standard Apple cover offered with the original Apple iPad launched in the June 2010 quarter. I whip it up and use it essentially as fast as I do any of my smartphones, all while walking on the streets. In fact, it is the closest thing to a smartphone substitute as I can imagine for my needs.

For example, I use Skype as my phone client; I make and take all of my phone calls from my iPad. All other apps are mostly the same as they are on the iPhone and iPod Touch. In addition, the iPad has an outstanding battery life, and I am not bothered by the extra weight. Then add the superior 10-inch screen for all sorts of reading and Web surfing, and I have found the iPad to be the superior mobile device, and for me it’s the most competent alternative to the BlackBerry. The iPad is truly the “one device to replace them all.”

So based on all of this, I have failed to understand why various reviewers complain about the 10-inch form factor, and instead have embraced the 7-inch tablets. But then it dawned on me: Hey, these people don’t live in California.

Yes, you heard me right: If you live in California, the iPad can be held in your hand, outdoors, everywhere you go, and basically be a substitute for even your smartphone. That doesn’t work if you live, say, near RIM’s Canadian headquarters where it’s cold in the winter, or in places where it rains heavily or often, even in the otherwise balmy U.S. southeastern states such as Florida.

This reminds me about the debate surrounding the suitability of electric cars. If you live in a climate that’s excessively hot, cold or humid, your range will suffer, often materially, making electric cars far less suitable for people living in North Dakota than in the ideal climate of Northern California, where it’s rarely too cold, too warm, or humid.

It may also explain why Apple went with the 10-inch tablet form factor, whereas RIM selected a 7-inch screen for its initial tablet entry. I hear from my Canadian friends that they wanted the device to fit in a jacket pocket. A jacket pocket? In California, you don’t need to wear a jacket, and therefore that’s not a consideration. It’s never cold and only rarely will you discover a light rain drop or two. I carry my iPad in my hand very close to 99% of the time, everywhere I go.

This only goes to show how heterogeneous this market is

RIM co-CEO Jim Balsille often refers to these new smartphone and tablet markets as “highly segmented” — and this may be as good an example as any. But who would have thought that the climate would be a huge factor in tablet screen size preference?

So there is my theory: People living in warm weather with less rain, such as California, will more often prefer larger tablets because they are carried in your hand outdoors 365 days a year. In contrast, people who live in colder climates, or where it rains a lot, are likely to prefer smaller tablets — such as the BlackBerry PlayBook — that can fit in a large pocket.

What should a tablet maker do? Just like a car company, which optimizes meeting demand by offering two-wheel drive cars, four-wheel drive cars, sedans, convertibles, gasoline, diesel, hybrid and all-electric cars, tablet makers ought to offer consumers living in different climates a choice. So far, only Samsung has announced a product portfolio to meet these varying demands, offering 7- 8.9- and 10.1-inch models. I imagine a company such as Apple offering 12- or 13-inch tablets in the future as well.

One final note: Apple made a big mistake when it it launched the iPad 2 with such a useless cover. Unlike the cover for the iPad 1 that came out one year ago, which was as flawless as any I have seen, the gimmicky cover for the iPad 2 is completely useless for those walking around with the iPad in their hands up and down the sidewalks. It does not offer any meaningful protection when you drop it onto the cement and asphalt. Hopefully, various companies will offer more suitable covers, ideally copying the one Apple itself offered for the iPad 1.

[Cross-posted at The Street]