- The air mass over the ocean is warm
- The air mass formed close to the ocean is humid in moisture
- Hence, the air mass over the ocean is warm and humid

- Unstable air mass can cause a thunderstorm
- Warm and humid air masses are usually unstable
- Therefore, warm and humid air masses can cause thunderstorms

- The air mass over the ocean is warm and humid
- Warm and humid air masses can cause thunderstorms
- Hence, the warm and humid air mass over the ocean can cause thunderstorms

- The warm and humid air mass over the ocean can cause thunderstorms
- Thunderstorms are a source of rainfall
- So, the warm and humid air mass over the ocean can cause rainfall

Hence, the warm and humid air mass over the ocean can cause rainfall
Q: What would a warm air mass over the ocean most likely cause?
Context:
- Unstable air mass can cause a thunderstorm 
- The air mass over the ocean is warm 
- The air mass formed close to the ocean is humid in moisture 
- Warm and humid air masses are usually unstable 
- Thunderstorms are a source of rainfall