Learjet 75 Captain reported during the initial climb suddenly heard a loud clunking noise and observed the left side windshield cracked. They notified ATC and returned to the airport.

Narrative

On Day 0; at approximately XA:06 hours; operating aircraft X on a Part 135 flight with XX passengers on board; an IFR flight plan and VMC weather conditions; departing ZZZ; while in initial climb through 9000 feet; I suddenly heard a very loud clunking noise and observed the left side windshield cracked. I immediately reduced speed to 180 kts and told the SIC to inform ATC of the situation and request vectors to address the situation and burn fuel; with which we were assigned 8000 feet and vectors to maintain north of ZZZ1 approximately 20 nautical miles. Subsequently I asked the SIC to run the QRH; then I turned the L WSHLD OFF; selected Manual Press ON; pressurization was Cabin Rate 0 FPM; cabin Delta P 1.3 psi. and Cabin Altitude 5300 feet. Once the QRH was completed I proceeded to configure the aircraft with flaps 20; landing gear down and speed 150 kts. After 1 hour of holding; aircraft was within the landing weight limit; and we notified ATC of our intentions to return to ZZZ2 and landed with no issues.