Temperature measurements are one of the most widely used parameters in weather. The temperature data that most people see in their hometowns on a daily basis come from sensors that sit approximately 6 feet (2 m) off the ground. Depending on the time of day, temperatures can vary by more than 2 or 3 degrees Fahrenheit from the sensors 6 feet off the ground to the immediate ground. In addition, different surfaces, such as green grass, black asphalt and many more, absorb and radiate heat differently. As a result of this variability, surfaces within a community will frequently show different temperatures based on color and location.
A recent Columbia University study led by researcher Stewart Gaffin looked into the temperature difference of surfaces based on color. Gaffin's study analyzed the daily temperatures of a flat green roof which included vegetation/grass that was 4 inches high, a flat white roof with a high reflectance and a flat black roof with a rubberlike membrane over the course of a year in New York City. His findings show that the black roof had a temperature of about 10 degrees F higher than either the green or white roof.
During the summer months, the difference in temperature among all three of the roofs was significantly different. Due to the higher sun angle along with the properties of each roof, the green roof with vegetation was on average 30 degrees F cooler than the white roof and 60 degree F cooler than the black roof. The black roof peaked at a temperature of 176 degrees F during the summertime. Temperatures this extreme are not uncommon for surfaces such as playground blacktops and asphalt roads on a hot summer day.
Weather plays a bigger role than you may think when it comes to seasonal outdoor allergies.
Why can different types of precipitation be seen on Earth while temperatures remain constant?
Dangerous flash flooding is captured as an arroyo becomes filled with water in Carson Valley, Nevada.
The RealFeel Temperature uses an equation to determine how it actually feels outside.
Knowing what the different advisories, watches, and warnings mean will lead to more informed decision making when a winter storm threatens a particular area.
How can you determine if and when the ice is thick enough for safely going out on?
Seeking shelter in the event of a tornado could save your life, but is there really any safe place to hide?
Driving on a 90-degree angle away from the tornado is a good strategy to follow in order to distance yourself from the tornado.
Supercell thunderstorms have been responsible for major tornadoes that have demolished parts of the U.S.
After a cold, clear winter night without much wind, the ground and nearby tree branches may be covered by tiny, white ice crystals.
College Park, MD ()
Tornado causes damage to buildings on Univ. of MD campus. 2 people were killed.
SC, GA & N FL (1888)
Southern frost, earliest frost ever so far south.
Yellowstone, MT (1926)
Minus 9 degrees F., lowest for U.S. in September. Severe widespread frost with great crop destruction. Earliest snow in Spokane Co., Washington.