Arrangement for levelling out environmental conditions around a levelling support of a geodetic instrument

The present invention relates to an environmental equalising arrangement for a support arrangement (3), which support arrangement (3) in use is adapted to support a registration device (4) and to provide an alignment opportunity for said registration device (4) in relation to a horizon. Said environmental equalising arrangement is provided with an environmental equalising feature such that an environmental condition within said support arrangement (3) in use is generally levelled out.