A Kelvin wave is making its way across the Pacific, prompting headlines about rising sea levels along the California coast. But what exactly is a Kelvin wave, how does it form, and what does it mean for California? Kelvin waves have been making headlines as an abnormally strong El Niño warms the Pacific and creates the conditions for these pulses of warm water to form. Now, Kelvin waves don’t break and can’t be surfed. But they can have significant effects on sea levels, coastal conditions and ocean temperatures. What is a Kelvin Wave? Kelvin waves are not tsunamis. They are a massive slow-moving pulse of warm water that moves deep under the ocean’s surface along the equator or a coastline. Unlike normal waves, you cannot see or surf a Kelvin waves. According to NOAA: “Unlike the waves you see at the beach, Kelvin waves do not curl over and then crash.   They are more like the waves in your bathtub, which slowly slosh around.…