Question

urban heat islands
urban heat islands refer to areas in and around cities that
are noticeably hotter compared to the nearby countryside.
they form due to factors like reduced vegetation and
increased heat - absorbing surfaces in urban settings. plants
usually absorb heat and provide shade, keeping
temperatures lower, but urban development replaces these
with surfaces like concrete and steel, which trap and reflect
heat. traffic and fuel combustion also contribute to the heat
buildup in cities.
scientists identify three main types of heat islands: surface,
canopy layer, and boundary layer heat islands. these
variations stem from factors like surface features, heat
absorption, and atmospheric conditions, all contributing to
the urban heat island effect.
surface heat islands are characterized by higher surface
temperatures in urban areas, visible in thermal images.
canopy layer heat islands occur closer to the ground, up to
the tops of trees or buildings, and result from warmer air in
urban areas.
boundary layer heat islands start at rooftops and extend
vertically up to a mile above the city, forming a vertical
heat island.
what do urban areas often replace
vegetation with, contributing to heat
islands?
farmland
more trees
concrete and steel
lakes and ponds

Explanation:

The text states that "urban development replaces these (vegetation) with surfaces like concrete and steel, which trap and reflect heat." This directly answers the question about what urban areas replace vegetation with to contribute to heat islands.

Answer:

concrete and steel