Routine radiosondes generally provide better measurements on ascent. This is due to the fact that the rise rate is relatively constant and that in most instruments the sensor is oriented such that ascent measurements are less contaminated from the instrument package itself. Descent measurements may suffer from time lag issues on fast descending parachutes or from self contamination of temperature measurements on radiosondes. Polymer humidity sensors fall from fast a region of no sensitivity (stratosphere) into a region of sensitivity (troposphere) and enter this region at cold temperatures. This leads to a significant lag that needs to be corrected. Slow descents of valved balloons may not always be feasible and may lead to stronger self contamination for ascent oriented sensors (usually temperature). This issue needs to be studied further before a quantitative statement can be given.