How could climate be extremely localized?

Question

What could be the reasons for climate to be so localized that it could rain in one street and not in the next, be extremely hot in a city and not in the next, have extremely narrow gusts of wind...

These changes are supposed to be random or at least somewhat unpredictable for lay people (the same way the weather is right now). If your explanation is that it is man-made, then I'm also asking how this technology could have unplanned side effects (at least so that lay people end up with localized weather).

I'm mainly asking for natural explanations (particular planetary system, tectonics or geographical layout), but answers are fine if they need to include futuristic explanations (post-punk type).

Answer 1

Hills and ridges.

• Even if the cities are all on the same elevation, the terrain features funnel winds.
• Shadow makes a difference, too.
• Then there is rain shadow.

The effect gets even more pronounced if the cities are at different altitudes.

Answer 2

Live in northern Nevada, right on the east slope of the Sierra Nevada. Seriously, that is perfectly normal, everyday weather hereabouts. I've seen it rain in my neighbors' pasture while my place - 100 yards away - is in sunshine. I can be outside in warm sunny weather, and watch snow/rain on the mountains less than 10 miles away as the crow flies - or I can be skiing in the sun on those mountains while my home in the valley is covered with dense freezing pogonip.

The wind likewise varies from place to place: "The "Washoe Zephyr" (Washoe is a pet nickname for Nevada) is a peculiarly Scriptural wind, in that no man knoweth "whence it cometh." That is to say, where it originates. It comes right over the mountains from the West, but when one crosses the ridge he does not find any of it on the other side! It probably is manufactured on the mountaintop for the occasion, and starts from there." -http://www.twainquotes.com/Zephyr.html

PS: I could also mention floating rocks and islands, moveable lakes, and the Jesus Cows :-)

Answer 3

In the physical world, mountainous terrain does have many of the effects that you describe. It could be sunny and relatively warm in Banja Luca, Bosnia, while just on the other side of the mountains it was snowing. For even more fun, the Adriatic coast had its own microclimate moderated by the sea.

So if your setting resembles the Balkans, or any similar region, then the effects are handed to you on a plate.

OTOH, the answer suggesting that this is the result of a high technology weather and climate control mechanism has some issues. The key difficulty is that weather and climate are adaptive, non linear systems and thus under the control of chaos theory. Since inputs and outputs are non linear, and often not directly related spatially or temporally, you will end up with all kinds of positive and negative feedback loops which cannot be effectively anticipated or controlled. The global system controlling such a climate control system would be quite massive and resource intensive, and even then would generally be running behind the climate as it attempts to analyze huge masses of data and inject energy or matter in the correct places to make the desired modifications. Even then, injections of matter and energy will cause secondary and tertiary effects that were not anticipated or correctly modelled, changing the global system yet again.

The one possible exception would be deliberate terraforming of the planet to create climactic microclimate zones, but even then that is only a temporary solution. Fluctuations in the solar constant, perturbations in orbits and other outside effects will cause climate changes like the "European Warm Period" and the "Little Ice Age" (and that covers the period from roughly the fall of Rome to the American Revolution)), while erosion and plate tectonics would eventually change the landforms responsible for creating the micro climactic regimes.

Answer 4

Rain on this side of the street and not that is perfectly normal in Hawaii. Kau Desert and Kau Rainforest are separated by an asphalt road along the border. Best rainbow-viewing is to stand down by Ala Moana Center on Keeamoku St., in the sun, and look up toward the Manoa Valley when the Manoa Mist is coming down in the afternoon.

Microclimates rule when the land is chopped up in mountains, valleys, and plains. Especially on islands just barely into the tropics.

Answer 5

For real, your question makes me think of drip irrigation and greenhouse technology. I can put a fruiting vine (which needs lots of water and several-times-daily spray over the leaves) right next to a plant that gets very little water and doesn't get the leaves wet in the sunlight.

The reason? Efficient utilization of resources (drip irrigation is exempt from yard water rationing) and flexibility, in a small space. Also, can create synergistic relationships that cross microclimates. For example, honeysuckle planted next to vegetables to keep the green lace wings life-cycle within a few feet, so they perpetuate and provide larva to keep pests from eating the cucumbers.

For that to happen on a larger scale implies intent, like a greenhouse. It would be weather control for the reasons noted above, for the city or planet as a whole.

It might be done with chaos: flapping a few butterfly wings here and there make it rain right over the tomatoes the next day.

Is it artificial as intentional weather control? Maybe leftover from a lost civilization, or installed by the original colonists before technology declined. Now it doesn't work to match any obvious needs. But, the corner where it rains a little every day is a perfect place for the vegetable garden...

An alternative would be evolved control by the biosphere. But I think such a system would go after robust control and feedback mechanisms, not seemingly magic subtle effects. It takes a lot of global awareness, planning, and computation to make it work.