Aurora over MF Radar

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The MF (Medium Frequency) Radar at Halley looks at wind speed and direction in the mesosphere - the section of the atmosphere between 60 and 100km above the ground. The radar uses a set of 6 cross-dipole antennas, each comprising a North-South and East-Wet dipole, five of which are strung between telegraph poles, and the sixth being buried in snow. The transmitting antennas illuminate patches of ionised gas, and the receiving antennas measure the signal that bounces back and track those patches as they drift across the sky. This then provides the strength of the winds.