Question

Explain why the distance between parallels is constant but the distance between meridians decreases as the meridians approach the poles.

Answer 1

The distance of parallel is always constant as it is the perpendicular distance from a point on one line to the other line so it does not matter which point is chosen to measure the distance. While for meridians  the distance between poles decreases as you near the poles as the circumference of the earth is lower as you near the poles.

Answer 2

The distance between the meridians decreases as you near the poles because of the lowering circumference of the Earth as you near the poles. To put it in a simple way, the Earth is a rounded body, elliptical, and the meridians are stretching from north to south, as they approach the equator the Earth is wider, so the distance between them become bigger, but as they approach the poles the Earth becomes narrower and they are coming closer and closer to each other until they finally all merge into one dot on each of the two poles.