Madison Isthmus (IMAGE) University of Wisconsin-Madison Caption Chilly winters may temporarily mask its effect, but the downtown Madison, Wisc., isthmus creates an urban heat island. According to a new study, the city's infrastructure leads to higher temperatures than its nonurban surroundings. Credit Jeff Miller/UW-Madison Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.