Space weather driven changes in lower atmosphere phenomena

6 During a period of heliospheric disturbance in 2007-9 associated with a co-rotating interaction 7 region (CIR), a characteristic periodic variation becomes apparent in neutron monitor data. This 8 variation is phase locked to periodic heliospheric current sheet crossings. Phase-locked electrical 9 variations are also seen in the terrestrial lower atmosphere in the southern UK, including an increase 10 in the vertical conduction current density of fair weather atmospheric electricity during increases in 11 the neutron monitor count rate and energetic proton count rates measured by spacecraft. At the 12 same time as the conduction current increases, changes in the cloud microphysical properties lead 13 to an increase in the detected height of the cloud base at Lerwick Observatory, Shetland, with 14 associated changes in surface meteorological quantities. As electrification is expected at the base of 15 layer clouds, which can influence droplet properties, these observations of phase-locked 16 thermodynamic, cloud, atmospheric electricity and solar sector changes are not inconsistent with a 17 heliospheric disturbance driving lower troposphere changes. 18