The aircraft can reach 21 km altitude, carrying a payload of 1.5 metric tonnes. It has only a single seat, so the instruments must operate automatically. The DLR Falcon is a converted executive jet, capable of carrying 4 scientists along with a two-man crew. The scientists carry out real-time analysis of results, which allows them to guide the Geophysica to invisible cirrus and other regions of interest. The tropopause is the boundary between the lower atmosphere, the troposphere, and the upper atmosphere, including the stratosphere and its ozone layer.
Air temperatures are generally lowest at the tropopause, increasing above and below.
A typical tropopause temperature over Europe or North America is -55 C. Cirrus clouds are high, thin clouds. In the tropics they can be formed at the top of convective systems, including cyclones, or by internal waves in the atmosphere causing local cooling. Both the Falcon and the Geophysica are equipped with instruments to measure the particles in sub-visible cirrus. Convection is the rapid vertical transport of buoyant air, which usually leads to cloud formation. If convection is sufficiently energetic, the air and cloud can reach the tropopause, where it can either deposit or remove water, depending on details of the cloud structure.