Today in our environmental science lecture, we'll discuss urban heat islands. As cities grow, they replace natural surfaces with concrete and asphalt, which absorb and retain heat. This effect is strongest at night, when buildings release the stored heat slowly. A key solution is increasing green spaces, like parks and green roofs, which cool the air through evapotranspiration. However, the effectiveness depends on the size and distribution of these areas. For example, a single large park can reduce temperatures more than several small ones scattered across the city. Also, lighter-colored materials on roads and rooftops can reflect sunlight, further reducing heat. So, urban planning must consider both green infrastructure and reflective surfaces.