Passage II

Large cities have their own climate that differs from the climate in adjacent suburban and rural areas. A scientist performed the following studies to learn more about an urban climate.

Study 1

Air temperatures, in degrees Celsius (°C), were recorded hourly over a 24-hour period at 3 sites: the center of a large city (the urban site), an adjacent suburban site, and a nearby rural site. This was done on 30 consecutive days during summer and 30 consecutive days during winter. Each hourly temperature was averaged over the given season. The results are in Figure 1.

Study 2

A site in the city was selected where a large concrete parking lot was located next to a large grassy area. After the parking lot and grassy area had been exposed to full sunlight for 8 hours, air temperature readings were taken at the surface every 20 meters (m) across the concrete and grass, starting at the center of the parking lot. The results are in Figure 2.

Study 3

Weather instruments were used to measure the wind velocity on 30 days at various altitudes above the 3 sites used in Study 1. The wind velocities, in kilometers per hour (km/hr), were used to generate the wind profiles shown in Figure 3.

Figures adapted from W. M. Marsh, Earthscape: A Physical Geography. ©1987 by John Wiley and Sons, Inc.

Study 4

The scientist kept track of the amount of cloud cover and precipitation daily for 3 years in the city and the rural area. It was found that the city had 10% more cloudy or hazy days and 10% more precipitation than the rural area. Air quality measurements revealed that the city air contained 10 times more dust particles than rural air.