To determine the highest point at which weather generally occurs, we can refer to the layers of Earth's atmosphere. The atmosphere is divided into several layers, which include:
1. Troposphere: This is the lowest layer where most of the Earth's weather events occur, such as rain, snow, and wind. It extends up to about 20 km above sea level.
2. Stratosphere: This layer sits above the troposphere and extends from about 20 km to 50 km above sea level. Weather phenomena are largely absent in this layer.
3. Mesosphere: Extending from 50 km to about 85 km above sea level, it is characterized by temperatures that decrease with altitude.
4. Thermosphere: This layer extends from about 85 km to 600 km or higher. Despite its high altitude, weather as we experience it does not occur here.
Given these layers and their characteristics, the troposphere is indeed the highest point where weather phenomena are commonly observed.
Therefore, the highest point at which weather generally occurs is:
A. 20 km
