Aspects of the invention are directed to a device and method for detecting characteristics of a gas. The gas includes an exhausted plume from a vehicle or factory plant, leaked gas from an oil well or gas resource, or unidentified gas from an unknown source. The method includes sweepingly directing a beam of light through the gas to a target surface on which the beam of light is scattered, acquiring the scattered light scattered from the target surface, and processing the acquired scattered light to determine the characteristics of the gas, where the characteristics of the gas comprise at least one of a temperature of the gas and an amount of at least one ingredient of the gas.