TT: Whither Weather

JANE: Last time we were talking about gale force winds in New Zealand.  How often do you get hit by them?

ALAN:Surprisingly frequently, particularly during the winter.

Flying into Wellington or Albuquerque

Flying into Wellington or Albuquerque

Wellington is actually nicknamed the Windy City – rather like Chicago in your neck of the woods and for much the same reason. We’ve run a couple of SF cons here, which we called Windycon of course, and once we got a full membership from a person in Chicago who wanted one of our T-Shirts so that he’d have bragging rights when he went to the Chicago Windycon…

Anyway, there was a severe weather warning for Wellington just a couple of weeks ago. We were all told about the possibility of roofs blowing off and the inevitability of power cuts as trees and power poles fell over. The winds arrived exactly as predicted and…

…absolutely nothing happened.

When it was all over, an official spokesman said, rather drily, “We’ve had so many gales this year that everything that can blow away has already blown away.”

JANE: That’s scary.  We get high winds here, but you have us beat.

 I bet a lot of people are blaming this on global warming.

ALAN: That might have something to do with the frequency with which these things occur, but there is evidence in the geological record that we have had very high winds in the past. There is a huge forest covering large parts of the top of the North Island. It is growing on top of the remains of one, or possibly two, much older forests which were completely destroyed long ago. As far as anyone can tell, the trees in these older forests had evolved large root systems that easily resisted the force of the prevailing winds. But one day a huge storm came in from an unusual direction and the trees, having no large root systems to protect themselves from those unexpected gales, were all uprooted, collapsing en masse.

Someone once asked, “If a tree falls in a forest and there is nobody there to hear it, does it make a sound?”

Well, maybe or maybe not. But when a whole forest falls over all at once, I imagine that it must be quite noisy!

JANE:  I’ve always hated that question…  It’s so humanocentric.  But I will resist ranting about that…   Suffice to say that existentialism and I did not mesh.

Other than worrying about having your roof blown off or your house getting crushed by a falling tree, how else do those high winds influence your life?

ALAN: I always get a bit of a sinking feeling in my tummy when I know the gales are on their way. I fly around the country a lot, and big winds can make landing at Wellington Airport more than a little hairy. The powers that be hate closing the airport because it causes so much disruption so it takes very extreme weather conditions indeed to close the airport down. Rumour has it that once you have landed safely at Wellington, you will never be scared in an aeroplane again. I’ve had far too many experiences of planes being thrown hither and yon all over the sky as they line up for the final approach…

JANE: Oh, dear.  I’ve always wanted to come back to New Zealand, but maybe I should make sure I don’t land in Wellington.  Turbulence and Jane do not mesh well.

A couple weeks ago, when I was coming home from my signing tour in California, my plane’s landing in Albuquerque was quite rough.  The skies were blue and bright, but a combination of winds and thermal updrafts made the plane buck like a bronco.  I’d been working for most of the flight, but I finally resigned myself to locating the airsick bag and hoping I wouldn’t need to use it.  I didn’t, but it was a close thing and I felt cruddy for the rest of the day – not precisely the homecoming I’d been imagining.

ALAN: I once read a novel in which a small child, seeking to amuse itself, went sneaking around an aeroplane when nobody was looking and cut the bottoms off all the airsick bags…

JANE: Oh, yuck!  I will now need to check in advance of every flight.

ALAN: You live in a desert which I always think of as being hot and arid, and yet the incident that started this discussion off was a hailstorm that damaged your roof. How can that happen in a desert?

JANE: Technically, I live in a high altitude grassland.  This is because Albuquerque gets seven and half inches of rain per year, rather than seven.  However, given that we’ve had drought conditions for the last several years, this is a moot point.

Deserts aren’t always hot and sunny.  Even at lower altitudes, the aridity can make for very hot days and extremely cold nights.  Albuquerque is at a mile high, so thirty degree temperature shifts are usual and fifty degree shifts are not unusual.  It’s quite possible for the temperatures to be warm enough that I’m wearing short sleeves during the day and covering my plants against a freeze at night.  That’s why even in mid-winter, the Indians could get a lot of use from their flat roof living space.

ALAN: Ah, I see. I wasn’t expecting that. Robin comes from Perth in West Australia. It’s a true desert town and every time I have been there (in summer anyway) it has always been very hot during the day and quite hot at night as well.

JANE: New Mexico has particularly odd weather.  I’ve watched it rain out of a clear blue sky.  The first time I went to Santa Fe, it was raining on one side of the street and not on the other.  I felt as if I was in a fantasy novel.

ALAN: New Zealand is a bit like that as well. We have quite a lot of geography cluttering up the country and that tends to divide the whole place up into a collection of isolated micro-climates. The weather forecasters make sweeping generalisations that are broadly true, but local conditions can override that, and the weather at one place can often be quite different from the weather just down the road.

JANE: Ah, microclimates!  Any gardener learns to deal with them, but here we really need to take them into account.

Not only does New Mexico get rain – when it does rain – out of a blue sky, I’ve also seen it raining up high – and the rain doesn’t reach the ground.

ALAN: Gosh! That’s bizarre. I’ve never seen anything like that.

JANE:  It’s not uncommon.  There’s a meteorological term for this: virgas.

ALAN: Wait!  Isn’t that what you called the Spanish roof beams that you mentioned a few weeks ago?

JANE: No, those are vigas.

ALAN: Oh, so perhaps we’re talking astrology then?  Are they named for the zodiac sign?

JANE: No…  That’s Virgo.  Admittedly, Virgos are known for being orderly, but I don’t think that extends to controlling whether or not rain touches the ground.

ALAN: So are you saying a virga is just like a raincoat for the ground – it keeps the soil dry in the same way that a real raincoat keeps you dry?

JANE: Absolutely!  Have I mentioned that you are a very silly human?

I just realized that we’ve mostly been focusing on the hot, dry, and windy.  I never did really get around to hail.  How about next time?


4 Responses to “TT: Whither Weather”

  1. Heteromeles Says:

    Well no, a virga’s what happens when the air closer to the ground is so hot and dry that the rain evaporates before it hits the ground. You can see virgas from quite a distance, because the sheets of rain under the clouds don’t touch the ground. Sometimes, if you’re lucky, the virgas moisten and cool the air enough that rain actually does hit the ground, but not always. We’ve seen a lot of them this year.

    As for rain out of a clear sky, usually there’s a raincloud upwind of you. Since that cloud may be most of five miles in the sky, a strong wind can blow the rain miles from the cloud, and you can be under blue sky when it lands on you. It’s an interesting experience.

    Happy monsoons, Jane!

    Speaking of weather-bound airports, my favorite is the Arcata airport up in extreme northern California, behind the redwood curtain as the locals say. That strip was supposedly set up in WWII so that the Army Air Corps could learn how to land in fog, as the area gets serious fog 300 days per year. After the war, they gave it to the community to be used as a commercial airport, and it still is, even though it still gets fogged in about 300 days per year. The major flights are to San Francisco airport, and it’s pretty common for Arcata flights to be delayed or even turned back because the fog in San Francisco has closed that airport. When this happens, it’s generally more foggy in Arcata than in SF, but whatever. Since the Arcata area is a pretty rural, there’s a move afoot to replace the control tower in Arcata with an unmanned radar beacon to save costs. With all that fog, no one needs to worry about telling the pilots about the ground conditions, right? A beacon is more than sufficient, don’t you think?

  2. Paul Says:

    I love that buildup to… Absolutely nothing happened.

  3. Sally Says:

    A local name for virga is “walking rain”, a term I am very fond of.

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