Urban Climates How does human activity affect climate? The Effects of the Urban Climate in the U.K. WHY? Urban Heat Island London night – May Why best at night? In high pressure? Where highest? Where lowest? Range? Draw a cross-section Urban heat Island cross-section – USA City Albedos Nearer to 1 = more energy reflected Car engines / exhausts Buildings with central heating Impact of parks? when greatest? Urban Rainfall Sun’s energy absorbed by buildings Decreased air pressure Increased air pressure Cumulus cloud where rising warm air meets colder air Convectional rain More dust particles for condensation nuclei Urban Winds • Wind is funnelled by tall buildings • Prevailing wind • Gusty winds may be two or three times stronger than average • ‘canyon’ effect of tall buildings Future Trends – different cities What are the advantages and disadvantages of the urban microclimate for a city dweller? What trends can we see for ‘all’ cities?