This green roof on top of Chicago’s City Hall saves the city approximately $5,000 a year in heating and cooling for the building and provides an urban garden space. As plants grow, they release water vapor into the atmosphere around them. How can increasing the coverage of green rooftops in an urban area help to reduce the negative impact of an urban heat island?

"a connection, a bond or common feeling between two people", or as a chemical process it stimulates love or sexual attraction

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.