山越えの道は狭く、しかも急勾配だった。

tbd

The road across the mountain was narrow, and what's more, it was a steep slope.

暖かい軽い空気は山越えすると上空に上昇し、地上には下りてこないことなど、風は地形によって変わります。

tbd

When warm, light, air crosses mountains it rises into the upper atmosphere and does not fall back to the ground. In this, and other, ways wind changes with the terrain.