# Waves, Breakers & Rip Currents Part of the Oceanography Merit Badge Digital Resource Guide: [Introduction & Overview](https://merit-badge.university/merit-badges/oceanography/guide/index.md) *3. Ocean Motion* > **3.** Describe the characteristics of ocean waves and do the following: Waves are moving energy, not giant lumps of water traveling unchanged across the sea. This requirement covers four important ideas: dangerous surge events, the difference between sea and swell, how breakers form, and how to stay safe around rip currents. **What to Watch When You Look at Waves** — Four clues that tell you what the water is doing - [ ] **Height**: How tall are the waves from trough to crest? - [ ] **Length**: How far apart are crests? - [ ] **Period**: How much time passes between waves? - [ ] **Shape near shore**: Are they steepening, breaking, or reforming? Video: [How Do Ocean Waves Work? (video)](https://youtu.be/_LRc6k-clzE?si=_bP0nKjcposT5QV5) ## Requirement 3a: Storm Surge, Tsunami, Tidal Wave & Tidal Bore > **3a.** Point out the differences among the storm surge, tsunami, tidal wave, and tidal bore. ### What each one is A **storm surge** is an unusual rise in sea level pushed ashore by strong winds and low pressure during a storm, especially hurricanes. It floods coasts and can move far inland. A **tsunami** is a series of large waves usually caused by an underwater earthquake, landslide, or volcanic event. Tsunamis can cross whole oceans and may look small offshore but become destructive in shallow coastal water. A **tidal wave** is a confusing old phrase that people often use when they really mean tsunami. True everyday tides are caused mainly by gravity from the Moon and Sun, not by storms or earthquakes. A **tidal bore** is a moving wall or surge of water that travels up a river or narrow inlet when an incoming tide is forced into a tight channel. ### The big differences - **Storm surge** comes from weather. - **Tsunami** comes from sudden displacement of water, often geologic. - **Tidal wave** is usually an inaccurate popular term. - **Tidal bore** happens in certain rivers or estuaries during strong tides. Video: [Tsunami vs Tidal Wave: What's the Difference? (video)](https://youtu.be/wk7RyUReaIA) Video: [What is Storm Surge? (video)](https://youtu.be/ZxYCB4VPVow) > **Tip** > > If someone says "tidal wave," ask what caused it. If the cause is an earthquake, it is a tsunami. If the cause is a hurricane, it is storm surge. ## Requirement 3b: Sea, Swell & Surf > **3b.** Explain the difference between sea, swell, and surf. **Sea** usually means choppy waves created by local winds blowing over nearby water. They are often irregular and messy. **Swell** is wave energy that has traveled away from the storm or wind that formed it. Swell waves are usually smoother, more organized, and more evenly spaced. **Surf** is the zone near shore where waves break. It is what you see at the beach when incoming wave energy hits shallow water and topples over. [Weather Explained: What's the Difference Between Seas and Swell? (video)](https://www.skynews.com.au/australia-news/weather-explained-whats-the-difference-between-seas-and-swell/video/836f58b40244e1a18c28b015033f9792): A quick visual explanation of why locally driven seas look different from organized swell. [Difference Between Swell and Surf (website)](https://support.surfline.com/hc/en-us/articles/4410126820891-Difference-between-swell-and-surf): A plain-language comparison that helps you separate incoming swell from breaking surf at the beach. Video: [The Difference Between SWELL and SURF (video)](https://www.youtube.com/shorts/qcwAsh9TDvo) ## Requirement 3c: How Breakers Form > **3c.** Explain how breakers are formed. Out in deeper water, a wave can travel forward without breaking because the base of the wave is not dragging on the bottom. As the wave moves into shallow water, the lower part begins to slow down because of friction with the seafloor. The top keeps moving faster for a moment, the wave gets steeper, and eventually the crest spills or crashes forward. That is a **breaker**. The slope of the beach matters too. Gentle slopes often produce spilling breakers. Steeper bottoms can create plunging breakers that curl and crash more dramatically. Video: [How Do Waves Break? (video)](https://www.youtube.com/watch?v=aXuQC1qRuEM) ![Step-by-step diagram of a wave steepening from deep water into shallow water until it breaks near shore](https://ik.imagekit.io/doulacoop/tr:w-800/mbu-assets/merit-badges/oceanography/guide/breakers-formation-sequence?v=ee5a61e8) ## Requirement 3d: Rip Currents > **3d.** Explain what a rip current is, how to avoid them, and what to do if you are caught in one. A **rip current** is a narrow, fast-moving channel of water flowing away from shore. Waves pile water onto the beach, and that water has to return seaward somehow. Sometimes it escapes in a concentrated stream between sandbars or beside structures like piers. ### How to avoid rip currents - swim at beaches with lifeguards - watch for posted warning flags - avoid areas with a darker, calmer-looking gap between breaking waves - stay away from piers, jetties, and sandbar cuts unless you understand local conditions ### What to do if you are caught Do **not** fight the current straight back to shore. That is how swimmers get exhausted. Instead: 1. Stay calm and float if needed. 2. Swim **parallel to shore** until you leave the narrow current. 3. Then angle back toward the beach. 4. If you cannot swim out, wave and call for help while floating. > **Safety First!** > > Rip currents can move faster than even strong swimmers. Your goal is to escape sideways, not overpower the water head-on. Video: [New Guide to Spot and Escape a Rip Current (video)](https://youtu.be/lofVgAzut6w?si=At3-3C6bldcYJI5Q) > **Be Prepared! If You Are Watching From Shore** > > If you see someone trapped in a rip current: > > - **Alert a lifeguard immediately** if one is present. > - **Call 911** if there is no lifeguard. > - **Throw, don't go** if you have a flotation aid. Do not create a second victim by rushing into dangerous water. Now that you understand moving water at the surface, the next step is to look below it at the landforms shaped by tectonics, sediment, and time. --- - Previous: [Seawater, Currents & Climate](https://merit-badge.university/merit-badges/oceanography/guide/req2/index.md) - Next: [The Shape of the Seafloor](https://merit-badge.university/merit-badges/oceanography/guide/req4/index.md)