Visualizing the Herlofson ’ s nomogram

On 1947, N. Herlofson proposed a modification to the 1884 Heinrich Hertz’s Emagram with the goal of getting more precise hand-made weather forecasts providing larger angles between isotherms and adiabats. From that date to nowadays, the Herlofson’s Nomogram has been used every day to visualize the results of about 800 radiosonde balloons that, twice a day, are globally released, sounding the atmosphere and reading pressure, altitude, temperature, dew point, and wind velocity. Relevant weather forecasts use such pieces of information to predict rains, thunderstorms, clouds height, fog, etc. However, in spite of its diffusion, non-technical people (e.g., private gliding pilots) do not use the Herlofson’s Nomogram because it is confusing and hard to read. The paper attacks this problem presenting an interactive visualization environment that allows for visualizing an Herlofson’s Nomogram in an easier way, selecting the right level of detail and inspecting at the same time the sounding row data and the plotted diagram.