Windows on Washington wrote:
Point of record...that window will leak air when it is half open like that at the meeting rail because of the lack of the interlock and weatherstripping contacting.
That's why you should always go to the hardware store and get an "air conditioning foam kit" so you can stuff the grey foam between the two sashes.

As an installer, I always kept a half dozen of these with me on the truck at all times for A/C units.