Case study US

Phoenix urban heat

Arizona

Phoenix illustrates how buildings, paving and limited moisture can influence urban temperature. Heat stored during the day can keep built surfaces warm after sunset.

Phoenix's skyline, transport surfaces and desert mountains seen from Sky Harbor airport. — Phoenix, Arizona. Built surfaces store heat in a desert city. Air or thermal measurements are needed to quantify the urban heat island; this photograph shows the land cover.

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Location: 33.45°, -112.07°

Urban surfaces differ from surrounding land in reflectivity, heat storage, shade and evaporation. Paving and buildings can store substantial energy, while limited soil moisture reduces evaporative cooling. The balance changes through the day and between neighbourhoods.

Compare surface properties in the energy-budget model. Ask students to distinguish a thermal image of surface temperature from an air-temperature measurement, then discuss how trees, shade and building materials alter local conditions.

Open this state in the lab

Exam-style question

Explain why a city can stay warmer than surrounding desert at night, using albedo and latent heat.

Teacher hint: Discuss heat storage, reduced evapotranspiration and surface properties, then explain why the urban contrast can persist into the night.

Process labs

Thermal circulation Earth’s energy budget

Sources

NOAA / NWS urban heat