Heat Islands

Heat Islands are created by the unique thermal characteristics in urban areas

Heat Islands

The average temperature of a city is typically slightly higher than that of the surrounding countryside.

Some days the city temperature may be as much as 10oC higher.

This “island” of warmer temperatures is called a heat island.

The Island idea suggests an isolated environment - one that is segregated from the surroundings

Heat Island intensity in Atlanta: Hotlanta

Why we should care about heat island effects…

1/6th of total electricity consumed in the U.S. is used for cooling, costing $40 billion per year. Also remember that electricity generates CO2

Air quality studies in Los Angeles estimate that a 1° F increase in summer temperatures boosts smog formation by 3%.

Increase in Ozone levels Students often confuse good versus bad ozone

HOW the land is used can help reduce the temperature

Why temperature and Ozone are connected

Ground Level Ozone Formation

Ozone is formed when nitrogen oxides (NOx) and volatile organic compounds (VOC) react with sunlight.

NOx is a by-product of high-temperature combustion created by automobiles and power plants.

VOCs include organic chemicals that vaporize easily, such as gasoline.

Ozone: The Bad and the Ugly Ozone reacts with the C=C

double bonds and breaks down the molecule into very reactive radicals.  These radicals then react further.  The end result is inflammation of the lungs. 

O3 irritates the respiratory tract and eyes.

Exposure to high levels of O3 results in chest tightness, coughing and wheezing.

People with respiratory and heart problems are at a higher risk.

Ozone has been linked to increased hospital admissions.

Impact: Weather

The Good…? From NASA city climates have a noticeable

influence on plant growing seasons up to 10 kilometers (6 miles) away from a city's edges. Growing seasons in 70 cities in eastern

North America were about 15 days longer in urban areas compared to rural areas outside of a city's influence

that for every 1 degree Celsius (C) or 1.8 Fahrenheit (F) that temperatures rose on average during the early springtime, vegetation bloomed 3 days earlier