The annual temperature range in regions with a tropical marine climate is small.

Tropical marine climate is characterized by warm temperatures throughout the year, with relatively small variations between seasons. This type of climate is typically found in regions near the equator, such as the Caribbean, parts of Southeast Asia, and the coastal areas of Central and South America.

Factors contributing to a small annual temperature range:
1. Latitude: Regions with a tropical marine climate are located near the equator, where the sun's rays are more direct and consistent throughout the year. This results in a relatively stable and warm climate, minimizing temperature fluctuations.

2. Proximity to water bodies: These regions are often located along coastlines or islands, with a significant influence from nearby oceans or seas. Water bodies have a high heat capacity, meaning they can absorb and store large amounts of heat. As a result, coastal areas experience moderated temperatures, with the ocean acting as a heat reservoir, preventing extreme temperature variations.

3. Prevailing winds: Tropical marine regions are influenced by trade winds, which blow from east to west in the tropics. These winds bring moisture from the ocean, leading to high humidity and limiting temperature extremes. The constant flow of moist air helps maintain a stable and relatively warm climate.

4. Cloud cover: The presence of cloud cover in tropical marine areas helps to regulate temperatures. Clouds reflect sunlight back into space, reducing the amount of heat reaching the surface. This natural cooling effect counteracts the potential for high temperatures, further contributing to a smaller annual temperature range.

5. Climate stability: Unlike regions with distinct seasons, tropical marine climates lack significant temperature variations throughout the year. The absence of cold winters or hot summers results in a more consistent and narrow temperature range, with average temperatures remaining relatively constant.

In conclusion, the annual temperature range in regions with a tropical marine climate is small due to factors such as latitude, proximity to water bodies, prevailing winds, cloud cover, and overall climate stability. These conditions contribute to a consistently warm and moderated climate throughout the year.