web-slinging action

I drew this while claire was out of town and spiderman 2 was on tv. I always try to get this particular effect with smoke and i always miss it. It's like a straight vertical line...rising and then a quick series of curves at the top like a sudden change in air density. It looks fluid in my head but i just can't make it work. If the pen hadn't died i think i would have made the shading encroach into the center shape a bit more....like near the name.