What is that instrument with two knobs and what looks like range rings?
WX-10 Stormscope


The WX-10 System consists of a display, remote processor, and an antenna. This Stormscope offers thunderstorm information on a bright green CRT display. The more the dots on the display are clustered together, the stronger the storm activity. Up to 256 dots may be displayed. The WX-10 also has a Forward mode to concentrate the display and processing power on the airspace ahead of you.
— bennettavionics.com

See also: Wikipedia: Lightning detection § Aviation use