City Centres and 2-3*c heat traps?!

[cordyman]

Everyday I leave my house and the car thermo matches the weather station +/- 0.5 *c

As I approach the city centre its always 2-3*c warmer, as I leave it drops by 2-3*c.

Last night went to the German Market and it was an impressive 15*c, got home to 12*c.

Is it the buildings trapping in heat/underground mass of power cables/sewers/mass of people in small area? or just a mix of all of that?

[GoggleboxUK]

I'd say it's the amount of stone and concrete holding the heat.

This is one of the reasons why I decided to block pave and get large concrete plant troughs as it definitely does create warmer temperatures in general. This summer I have always been between 3 and 8c warmer than the Preston Weather Station.

Bear in mind that the average temperature of the Earth at 1m deep os 12c and heat rises.

[Exotic Life]

Well look to your big city London, how big those differences can be. They have done some reasearch very recent in one of our big city's Rotterdam. They have seen differences up to 8/9C between the middle of the city and just outside the city.

[stephenprudence]

its a mix between wind being funnelled up streets and and heat coming from car exhausts and heat escaping from buildings

[GoggleboxUK]

I can't see how heat escaping from buildings could apply Stephen. Aren't most buildings much taller than the 2 metres they take the readings at?

Surely heat rising from houses occurs at a higher level than that let alone the multistorey shops, offices and tower blocks you'd normally associate with big cities?

[Yorkshire Kris]

I can't see how heat escaping from buildings could apply Stephen. Aren't most buildings much taller than the 2 metres they take the readings at?

Surely heat rising from houses occurs at a higher level than that let alone the multistorey shops, offices and tower blocks you'd normally associate with big cities?

Heat emanates from all directions out of a building. That's why it's good to move pots near a house wall for the extra heat. (It does eventually rise upwards)

[MikeC]

It's all explained here

http://en.wikipedia.org/wiki/Urban_heat_island

Mostly the effect is due to masses of materials that absorb heat and radiate it slowly back such as concrete, brick, stone, tarmac, paving etc. Acts like a giant storage heater during the day, keeping the overnight mins much higher than the countryside.