Note: This talk will be about microwave radiometry and not microwave ovens. Radiometry is a powerful tool for atmospheric remote sensing. It enables the measurement of very weak signals from trace gases in the atmosphere such as chlorine monoxide (ClO) and bromine monoxide (BrO), the two largest ozone depleting substances in the stratosphere. The precise measurements require accurate instrumentation as well as a good knowledge of the atmosphere and the target molecules themselves. This talk will present radiometry from its humble beginnings at the turn of the 20th century, it's successes in the field of atmospheric sounding, and the work currently being done at UofT with the construction of a state-of-the-art superconducting microwave receiver.