Local Micro Climates (snowing, record, temperature, rainfall)
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Do you have any significant micro climates close to where you live?
I've never seen frost on some paddocks below here, even though the area gets about 70 frosts a year. A down slope wind on colder mornings stops frost forming. Even on the coldest morning I've ever seen here (-5.8C/22F) there was only heavy dew on the grass. Less than 1 km away, are shaded spots where frost can stay for 10 days or so during really cold spells.
I would be interested in other micro climates. Hot, cold, wet, windy, whatever. They don't need to have official readings or anything.
Can't think of anything as marked as that (I bet with your topography NZ must be one of the top places on Earth for microclimates) but I'm curious as to why Greenwich and Heathrow in London have over 100 hours' difference in annual sunshine when they are not more than 15-20 miles apart, have very similar altitude and neither is by the sea. I find frost hollows and temperature inversions pretty interesting. I read an (unsubstantiated) report of Altnaharra, a frost hollow in northern Scotland recording -22C one day last year when the mountaintop right by it was at +3 at the same time.
Can't think of anything as marked as that (I bet with your topography NZ must be one of the top places on Earth for microclimates) but I'm curious as to why Greenwich and Heathrow in London have over 100 hours' difference in annual sunshine when they are not more than 15-20 miles apart, have very similar altitude and neither is by the sea. I find frost hollows and temperature inversions pretty interesting. I read an (unsubstantiated) report of Altnaharra, a frost hollow in northern Scotland recording -22C one day last year when the mountaintop right by it was at +3 at the same time.
Presumably Greenwich has a good open position for sunshine recording? It would be a poor look if a famous observatory couldn't organise a decent "exposure".
Presumably Greenwich has a good open position for sunshine recording? It would be a poor look if a famous observatory couldn't organise a decent "exposure".
It's an official station so you'd assume it met whatever standards there are, but I haven't been to the observatory since I was a kid so couldn't tell you about its position (and ditto for Heathrow as I've never been there at all). Hampstead's sunshine figures are more like Greenwich's from what I've seen (I haven't seen the actual 30-year average but most individual years seem to be high 1400s/low 1500s) but it would make sense it being less sunny there with 300ft extra elevation.
Location: The western periphery of Terra Australis
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Originally Posted by ben86
Can't think of anything as marked as that (I bet with your topography NZ must be one of the top places on Earth for microclimates) but I'm curious as to why Greenwich and Heathrow in London have over 100 hours' difference in annual sunshine when they are not more than 15-20 miles apart, have very similar altitude and neither is by the sea. I find frost hollows and temperature inversions pretty interesting. I read an (unsubstantiated) report of Altnaharra, a frost hollow in northern Scotland recording -22C one day last year when the mountaintop right by it was at +3 at the same time.
Actually heat island effects have been known to create more moisture/humidity/condensation and thus more rainfall, so the CBD's of large cities do indeed tend to be marginally wetter and cloudier than surrounding countryside.
I've been to Greenwich, very interesting place! Took the boat to the Naval Academy/Museum then it was a rather long walk to the top of a hill to the observatory. It was in the open as I remember although there were some trees. I would say the location would be the variance, it is on a knoll, river not that far away. Heathrow on the other hand would be flat right??? I've been there, 3 or 4 times, but only to fly in and out, not paying attention to topography, surrounding area.
I was last there in late 90's, I think. Somewhere I have a card time stamped, stating I was at 0 longitude, Royal Observatory, I'm not sure what else it says.
I mentioned Two Rivers/Manitowoc where I live in a rep to you but trouble with checking them out is some sites list Manitowoc temps for us, not happening. Trouble with some Manitowoc readings they are taken by the airport, which is away from Lake Michigan.
Yesterday Manitowoc was 62, when I drove home it was 48. A distance of less than 10 mis. However, weather data on the site someone mentioned shows it to be the same, very rarely does that happen. Now when I check the weatherbug for yesterday, it shows TR at 52 (mine said 48) and Manitowoc by the airport 65.
Once the sun goes down, our evening temps can be closer together, that happens. I find it very interesting and a subject of discussion on C-D when I hang out at the Wisconsin chat thread!
Actually heat island effects have been known to create more moisture/humidity/condensation and thus more rainfall, so the CBD's of large cities do indeed tend to be marginally wetter and cloudier than surrounding countryside.
Yeah, I remember hearing something about the urban heat island effect significantly strengthening and increasing convective thunderstorms, and that areas downwind of cities measure more precipitation than upwind.
There are some noticeable microclimates here particularly with precipitation. In winter especially, it can be sunny in one part of the city, raining in another and snowing in another. It all depends on distance from water and elevation. Several mornings in winter, I've left my house in the suburbs and it has been snowing or sleeting and when I arrive at work downtown, it's just cold rain.
Several mornings in winter, I've left my house in the suburbs and it has been snowing or sleeting and when I arrive at work downtown, it's just cold rain.
I get that kind of experience too, commuting from north of Toronto to downtown, which I'd attribute to the urban heat island and distance from the lake.
On a related note, I wonder how large a city usually has to be in order to have a noticeable heat island effect (correcting for the natural variation in parts of a the city such as elevation or closeness to water). Any city with many millions of people (London, NYC etc.) would seem to have it quite strongly noticeable.
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