ROBOT.LK

This serene image is from HALO – not the shoot-'em-up sci-fi videogame, but the High Altitude and Long Range Research Aircraft. The modified Gulfstream jet captured this image on its latest mission to measure cloud properties above Brazil's rainforests to better understand their impact on climate.

Flying close to, or even through, tropical thunderclouds like this one is not easy. HALO pilots had to fly at altitudes of up to 15 kilometres, in temperatures that swung 100 °C, from 35 °C on the ground to -65 °C in the upper troposphere.

The flights investigated how clouds in clean rainforest air differ from those found over polluted and deforested regions, or above burning vegetation. Preliminary findings suggest that polluted clouds tend to hold more water droplets than clean ones, but that these droplets are much smaller.