The annual range of temperature in equatorial regions is relatively small, typically ranging from 0 to 5 degrees Celsius. This is due to the unique climate characteristics found in equatorial regions.

1. Equatorial Regions:
Equatorial regions are located near the equator, which is an imaginary line that divides the Earth into the Northern Hemisphere and the Southern Hemisphere. These regions receive direct sunlight throughout the year, resulting in a warm climate.

2. Climate Characteristics:
Equatorial regions have a tropical climate characterized by high temperatures, high humidity, and abundant rainfall. The consistent direct sunlight and proximity to the equator create a relatively stable climate throughout the year.

3. Low Annual Temperature Range:
The annual temperature range in equatorial regions is limited due to the constant heat received from the sun. The high amount of solar radiation leads to a warm climate throughout the year, preventing significant temperature fluctuations.

4. Factors Influencing Temperature Range:
Several factors contribute to the small annual temperature range in equatorial regions. These include:

- Solar Insolation: Equatorial regions receive high solar insolation, meaning they receive a significant amount of solar radiation throughout the year. This constant heat input keeps the temperatures relatively stable.

- Atmospheric Circulation: The consistent heating at the equator causes warm air to rise and travel towards the poles. This creates a continuous circulation pattern known as the Hadley Cell, which helps maintain the temperature stability in equatorial regions.

- Ocean Influence: Equatorial regions often have a maritime climate due to their proximity to oceans. Oceans act as heat sinks, absorbing and releasing heat slowly, which further contributes to temperature stability.

5. Other Climate Characteristics:
In addition to the small temperature range, equatorial regions also experience high humidity and abundant rainfall. The combination of heat and moisture creates a favorable environment for lush rainforests and diverse ecosystems.

In conclusion, the annual range of temperature in equatorial regions is typically 0 to 5 degrees Celsius. The consistent solar radiation, atmospheric circulation patterns, and ocean influence contribute to the small temperature fluctuations in these regions.