Practice Tests
IELTS Reading (AC) Task 1 #78

A. Cities are often warmer than the countryside that surrounds them, a pattern known as the urban heat island. The effect emerges from the way urban materials store and release energy. Asphalt and concrete have low reflectivity and high heat capacity, so they absorb sunlight by day and release it slowly after sunset. Tall buildings reduce wind flow and create street canyons that trap warm air. As a result, nighttime temperatures in dense districts can remain several degrees Celsius above nearby rural areas, especially during clear and windless conditions.|Multiple causes reinforce one another. Vegetation is scarce in many city cores, which limits shade and evapotranspiration, the natural cooling provided when plants release water vapor. Dark roofs and pavements amplify solar gain, while traffic, air conditioning units, and industrial equipment add waste heat directly to the air. Urban geometry also matters. Narrow streets with high walls limit the portion of sky visible from the ground, which reduces the efficiency of longwave radiation to space and delays cooling.|These physical processes have social and economic consequences. Elevated temperatures increase demand for electricity as residents run air conditioners for longer hours, which can strain power grids during heat waves. Warm air can worsen air quality by accelerating the formation of ground level ozone. Health risks rise as bodies struggle to shed heat at night, and the burden is not evenly shared. Low income neighborhoods often have fewer trees and more impermeable surfaces, which raises exposure even when two districts are only a few blocks apart. Schools, outdoor workers, and the elderly are particularly vulnerable.|Mitigation strategies are well studied and increasingly practical. Cool roofs and reflective coatings raise surface albedo and can lower indoor temperatures without additional energy use. Green roofs and pocket parks add shade and promote evaporative cooling. Expanding urban tree canopies improves comfort, reduces glare, and offers habitat benefits, though species selection must reflect local water availability. Permeable pavements and light colored aggregates can reduce surface heating while managing stormwater. Some cities also protect breezeways or ventilation corridors in their zoning rules so that prevailing winds can flush hot air from dense districts.|Measurement and governance shape outcomes. Satellite thermal imagery provides broad maps of surface temperature, but ground based sensors capture the air that people actually breathe. Crowdsourced data from portable loggers and neighborhood surveys can reveal hot spots that city averages hide. Effective heat action plans combine early warnings, cooling centers, building codes, tree maintenance, and utility programs that reward off peak cooling. Because urban form evolves over decades, the most durable gains come from integrating heat resilience into routine decisions about roofs, streets, and public space.