[ChuckS]

I'd suggest moving away from thinking condenser vs dynamic mics. Yes, dynamics have lower sensitivity, but you will probably have to add more preamp gain using a dynamic mic so you will be applying this additional amplification to both the signal you want and as well as the ambient noise.

You may want to focus on how to get your desired signal level higher and/or getting the recorded ambient noise lower.
(1) A directional mic (cardiod, etc) should help in the ratio of desired signal to undesired noise.
(2) Soundproofing to lower ambient noise probably won't be practical, so your options may be limited to recording during times where the outdoor ambient noise is low (late at night?)
(3) In order to get your desired signal level higher relative to the ambient noise you could mic closer to your source. How close you mic to your source(s) can factor into what type of directional mic you choose (cardioid, wide cardioid, hyper cardioid, etc). Also, a directional mics distance from the source affects the magnitude of its proximity effect (boost of lower frequencies). You can get mics designed for close micing, or you can E/Q to offset the proximity effect.

So, I'd suggest recording when the outside ambient noise is lowest, getting directional condenser mics, and record as close as necessary to improve signal to ambient noise ratio. Note: As you record closer to the source the recording may not sound as realistic. That's a tradeoff.