  With a rapid increase in the number of geostationary satellites around the
earth's orbit, there has been a renewed interest in using Global Positioning
System (GPS) to understand several phenomenon in earth's atmosphere. Such study
using GPS devices are popular amongst the remote sensing community, as they
provide several advantages with respect to scalability and range of
applications. In this paper, we discuss how GPS signals can be used to estimate
the amount of water vapor in the atmosphere. Furthermore, we demonstrate the
importance of such precipitable water vapor (PWV) in the atmosphere for the
task of rainfall detection. We present a detailed analysis in our dataset of
meteorological data of 3 years. Test dataset shows that use of PWV in rainfall
detection helps to reduce the false alarm rate by almost 12%.
