Şehirler Neden Sıcak — B2 İngilizce Okuma Parçası

On a summer night, a thermometer in the centre of a large city and another one in the fields outside it will not agree. The difference is often three or four degrees, and in extreme cases much more. The two instruments are measuring the same weather. What they are not measuring is the same ground.

The cause is the surface. A field is covered with plants and loose soil; a city is covered with concrete, stone and asphalt. These materials are dense and dark, and they absorb far more of the sun’s energy during the day. A road in the direct sun can reach a temperature that would burn skin, while the grass beside it stays close to the temperature of the air.

Absorbed heat has to go somewhere, and it comes back out slowly after the sun goes down. This is why the gap between urban and rural areas is smallest at midday and largest around midnight. The countryside cools quickly once the sun is gone. The city spends the whole night giving back what it collected. The problem is not that cities are warm; it is that they stay warm, and a body that never gets a cool night recovers badly from a hot day.

Plants work against this in two separate ways. The first is obvious: a tree throws shade, and shaded concrete never gets hot in the first place. The second is less visible but just as powerful. Leaves release water, and when that water evaporates it takes energy with it. A large tree can move hundreds of litres in a single day, and every litre carries heat away. A street with mature trees can be several degrees cooler than an identical street without them.

Colour matters too, for the same reason that a black shirt is uncomfortable in July. Dark surfaces absorb; pale surfaces reflect. Several cities have begun painting roofs white, and the measurements are consistent: a white roof can be thirty degrees cooler than a black one on the same afternoon, and the rooms below it need far less cooling.

None of these findings is difficult or expensive to act on. Trees, pale surfaces and open water are old ideas, and the older parts of many hot cities already use all three. What changed is that we can now measure the effect precisely, which turns a matter of taste into a matter of engineering.

Why Cities Are Hotter — Şehirler Neden Daha Sıcak

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