This is the 9756th most frequent Russian word.
экваториальной
Relating to the equatorial region.
Here, 'экваториальную' is used as an adjective to describe 'part', indicating its geographical property of being near the Earth's equator.
Путешественники пересекли экваториальную часть Африки.
The travelers crossed the equatorial part of Africa.
In this sentence, 'экваториальным' refers to the type of climate typical near the equator.
Климат в этом регионе считается экваториальным.
The climate in this region is considered equatorial.
The term 'экваториальные' is used to describe 'air masses', specifying that they originate or are located near the equator.