(a) What is the primary basis for the division of the atmosphere into different regions? (b) Name the regions of the atmosphere, indicating the altitude interval for each one.

The primary basis for the division of the atmosphere into different regions is the temperature gradient or temperature changes with altitude. Different layers of the atmosphere exhibit different temperature characteristics, which is the main reason for their categorization.

The atmosphere is divided into five major regions, based on temperature characteristics and altitude: 1. Troposphere: The troposphere is the lowest layer of the atmosphere, extending from the Earth's surface up to an altitude of approximately 8-14.5 km, depending on the location (higher at the equator and lower at the poles). The temperature in this region decreases with increasing altitude. 2. Stratosphere: The stratosphere lies above the troposphere, with its lower boundary starting at around 8-14.5 km, and extending to approximately 50 km. The temperature in this region increases with altitude due to the presence of the ozone layer, which absorbs ultraviolet radiation from the Sun. 3. Mesosphere: The mesosphere is located above the stratosphere, with its base at about 50 km and extending up to roughly 85 km. The temperature in this region decreases with altitude, with the top of the mesosphere being the coldest part of the atmosphere. 4. Thermosphere: The thermosphere starts at around 85 km and extends up to approximately 600 km. This layer experiences a significant increase in temperature with altitude due to the absorption of highly energetic solar radiation by its sparse gas molecules. 5. Exosphere: The exosphere is the outermost region of the atmosphere, starting at around 600 km and extending up to about 10,000 km. This is the transition region between Earth's atmosphere and outer space. The temperature in this region is highly variable, depending primarily on solar activity. Note that the boundaries between these regions are not sharp, and there are transition zones called "pauses" between these layers.