LIDAR

source: http://rst.gsfc.nasa.gov/Sect8/Sect8_8.html

LIDAR (Light Detection And Ranging) is similar in concept to radar technology but instead of using radio waves to determine range to an object, LIDAR uses laser pulses (

measuring the time delay between the transmission of the laser pulse

and the detection of the reflected signal). Because LIDAR uses shorter wavelength pulses than radar, it is able to detect very detailed objects such as aerosol particles in the atmosphere. LIDAR was used to determine the varying heights and angles of the cityscape shown in the map above!