Nature

7. A cascade of water falling from a height, often over rocks or cliffs
8. A landform that rises high above its surroundings
11. A large and sudden rise and fall in the sea level caused by gravitational forces of the moon and sun
13. An overflow of water that submerges land
14. A natural watercourse that flows towards an ocean, sea, lake, or another river
16. A rotating column of air that forms from severe thunderstorms
17. A tropical cyclone with strong winds and heavy rain
18. A multicolored arc in the sky caused by the refraction of light in water droplets

1. A sudden and powerful discharge of electricity in the atmosphere
2. A barren area with little precipitation and sparse vegetation
3. A diverse underwater ecosystem made up of colonies of coral polyps
4. A sudden and violent shaking of the ground caused by the movement of tectonic plates
5. A large mass of ice that moves slowly over land
6. The daily disappearance of the sun below the horizon
9. A sandy or rocky shore by the ocean, sea, or lake
10. A deep and narrow valley with steep sides
12. A mountain with a vent through which lava, rock fragments, ash, and gas erupt
13. A large area dominated by trees and undergrowth
15. A natural light display in the sky, also known as the Northern Lights or Southern Lights
19. A vast body of saltwater that covers much of the Earth's surface