Twice a day, everyday, at 1300 stations around the world, weather balloons carry instrument packages up through the troposphere and radio back valuable information that greatly adds to our weather prediction capabilities. This packet introduces students to the concept of atmospheric stability and by calculating the Total Totals (TT) index, illustrates how meteorologists quantify stability in order to help them predict thunderstorms and tornadoes.

The five in-depth activities use real-time data available on-line from NOAA's sounding stations located across the U.S. These activities support and help to reinforce the student's graphing and interpretation skills and gives them a greater understanding of the complexities of weather forecasting.