[who_would_fardels_bear]

Nowhere in the article do they explain exactly how the spiders' use of static electricity allows them to fly. In fact, they hint that they are still trying to figure it out.

If all of the strands of web are negatively charged and the Earth's surface is negatively charged with respect to the clouds, then it would make sense for the spiders to be repelled away from the Earth and toward the sky.

This would explain their ability to launch quickly from the ground even in low wind conditions.

However, in order to move across the Earth they would either have to be blown by the wind or they would have to encounter some sort of lateral voltage gradient.

[DUMBGRUNT]

A bit more here:
https://arxiv.org/abs/1309.4731