Evening launch. The aerological balloons routinely ascend to altitudes of >40 km, and during the IONS 2006 program O3 profile data were collected to an average height of 33,135 meters. Since pressure is one of the parameters measured, and always decreases with altitude, it can be used to indicate the vertical dimension. Thus the primary measurements taken by the radiosonde are reported as a function of pressure rather than height (i.e. in millibars, “mb”).