As urban areas develop, changes occur in their landscape. Buildings, roads, and other infrastructure replace open land and vegetation. Surfaces that were once permeable and moist become impermeable and dry. These changes cause urban regions to become warmer than their rural surroundings, forming an “island” of higher temperatures in the landscape.
Heat islands occur on the surface and in the atmosphere. On a hot, sunny summer day, the sun can heat dry, exposed urban surfaces, such as roofs and pavement, to temperatures 50–90°F (27–50°C) hotter than the air1, while shaded or moist surfaces—often in more rural surroundings—remain close to air temperatures. Surface urban heat islands are typically present day and night, but tend to be strongest during the day when the sun is shining.
Surface and atmospheric temperatures vary over different land use areas. Surface temperatures vary more than air temperatures during the day, but they both are fairly similar at night. The dip and spike in surface temperatures over the pond show how water maintains a fairly constant temperature day and night, due to its high heat capacity.
Final Destination for Punjab PSC Notes and Tests, Exclusive coverage of PPSC Prelims and Mains Syllabus, Dedicated Staff and guidence for Punjab PSC PPSC Notes brings Prelims and Mains programs for PPSC Prelims and PPSC Mains Exam preparation. Various Programs initiated by PPSC Notes are as follows:-- PPSC Mains Tests and Notes Program
- PPSC Prelims Exam 2024- Test Series and Notes Program
- PPSC Prelims and Mains Tests Series and Notes Program
- PPSC Detailed Complete Prelims Notes