all right class so we left off here uh checking your understanding uh with one of the variables we talked about with regard to ocean waves and this has to do with whether or not it's a deep water wave or shallow water wave if you didn't understand this uh please refer back to the video previously um just in recap we did wavelength we did wave speed we did wave height we did you know crest and trough we did period we did wave base we did the difference between deep water waves and shallow water waves we also talked about dispersion and fetch right so all those things i definitely want you to know um and i might not be saying everything that you need to know right now um you got to go back to that previous video make sure you watch that and get everything you can from it but today we're going to continue on with waves we're going to talk about some different types of interference constructive and destructive and mixed interference we'll also talk about some rogue waves and and the difference between also refraction and reflection when it comes to waves so let's get into it um let's make our way through we're going to finish up with tsunamis by the way and uh yeah hopefully um you get something out of this that you uh you enjoy so let's take a look now here we are i want you to know these three different types of interferences okay so think about in the ocean you got two different sets of waves right two waves and if they line up in a way in which they end up being exactly in the same spot at the same time what that leads to is something called constructive interference okay so this occurs in waves of the same wavelength come together in phase okay so that means that their crest and crest are lined up and trough to trough are lined up and they produce waves of a greater height so this is a constructive interference all right the opposite of that would be something called destructive interference and that's when the crest and the trough of another wave line up and the trough and a crest of another wave line up so it occurs when overlapping waves have identical characteristics but come together out of phase so this is an in phase result and this is a out of phase result with destructive interference what results is something where you end up with no wave resulting right so it totally cancels itself out both of these constructive and destructive interferences are things that surfers know all about okay so a term that you might use when you're surfing is you're looking for double ups right you're looking for waves that kind of double up make make themselves bigger and greater that's because you know what constructive interference is without even knowing you know what constructive interference is right a double up that's a constructive interference wave at the same time sometimes waves come in out of phase and it looks like a set's coming but then it doesn't quite break and it doesn't all work out that's destructive interference where all all of a sudden there's not really much of a wave and you couldn't surf it and and that's just how it goes that's destructive interference now what we always have going out on the ocean is something called mixed interference okay this occurs when waves of different wavelengths and heights overlap one another producing a complex wave pattern of course in the ocean it's not just constructive or destructive it's a mixture of both so in this case we've got something with a period that might be longer or longer wavelength and here got shorter period and shorter wavelengths and they're happening at the same time within the ocean what this results in is something called a mixed interference so this one in the middle might be somewhat of a double up where here these are kind of canceled out like so this is kind of constructive interference here and then this is slight destructive interference here i want to show you another way you could kind of see this using this earth guide diagrams okay this is from ucsd and we're going to mess with different variables with wavelengths all right and periodicities so i'll take you there now and we'll check in with that let's go okay so this is a really useful tool in order to look at differences in waves and constructive and destructive interference so what we have here this red line behind right if you just pause this this red line behind is actually got a stacked green line behind it okay and that represents two individual waves and this white line is the addition of those waves so that's what is making it see it's right now since they're in phase you can't see the green wave behind let me show you that it's that it's there if i stack them you can see look at this here's the green wave behind or blue whatever color you might think it is right and then you got the red wave these are both individual wavelengths and periods but then if i layer them you'll see oh there it is it's behind there okay and this white line is the addition right this is constructive interference right now because the trough and the trough and the crest and the crest are lined up resulting in greater crests so taller wave heights right um so let's stack them again or layer them again and play this and now what you can see is i can mess with the wave a or wave b with their speed or amplitude or wavelength right so let's change the wavelength of wave a behind a little bit now are you seeing how this is a mixed interference now right so the wave the blue wave is actually starting to move quicker if you follow it's moving faster than the red wave therefore resulting in constructive interference here because it's in phase but then it's totally out of phase here let's pause it you can see look at this it's perfectly out of phase right here right resulting in this white line which is what you're going to see at the ocean which is kind of like no waves but if you look back here they're almost perfectly in phase making the waves look much taller right so this is that double up and here's where it's not a double up it's totally cancelled out in phase out of phase right so there's all sorts of ways in which you can mess with this if we bring the wavelength back then it's back to perfectly constructive interference we could change the amplitude of the green wave behind so you could see it and if i change the amplitude it's an extra double up so you can see that the um addition has created an addition to the resulting white line which is what you're going to see at the beach now let's change the wave speed we'll slow down wave a now if we slow it down now you can see once again wave b is moving faster but now it's going in phase now and then back to out of phase right here so you can see how these troughs and crests are slowly lining up this is what you're seeing out in the ocean um the white line is what you see all the time and the red and green lines are these different um wave lengths and periods out in the ocean right so for instance there's there's various swells occurring every day so you might have a swell from the southwest it's a 15 second period and it's a wave height of 2.5 feet you might also have another swell that's from the northwest that's at three feet um and it's got a period of 17 seconds those two swells are kind of here represented as the green and red lines and what you see in the ocean is what the white line is right how they interact that's what you're going to see so yeah i mean this applies directly to the ocean i hope that you go to this website and mess around with this because it's it's actually quite a bit of fun um and if we looked at the stacked part you could see look see here's the green wave moving faster and this red wave moving slower because this would be a longer wavelength potentially shorter wavelength longer wavelengths move faster and this is the resulting double up or should i say in phase or out of phase all right so we'll stop there and head back to lecture now i hope that was helpful and i hope that you go and check out that website because it's really fun to mess with and you can really learn a lot about how those two different waves can interact creating constructive and destructive and mixed interferences with each other and i think that tool that they have their ucsd is a great tool to use from that what this results in sometimes right not just surfing right but also into rogue waves okay so rogue waves happen it says here it's it's when a strong ocean current right such as the ghoulhouse current which which happens off the uh coast of south africa right at the bottom the southern end these flow in the opposite direction of large waves right so such as those in the antarctic waters so down in the southern ocean that's where the largest waves in the world are created and if you have a current that's going in the opposite direction for instance here you see how an antarctic storm wave movement is going from right to left and then your ghoulhus current is going from left to right they might form a big wave just like this and if this ship was making its way it might get sunk right here by this huge wave right and this happens rogue waves occur if anyone has seen that movie perfect storm you might have seen a representation of what a rogue wave would be like right so road waves happen they cause major destruction for instance here's a shot off a ship here at running into giant seas and potential rogue waves in which the water is overflowing the bow of the ship much like that video i showed you uh in that last lecture video where they were kind of laughing in the cockpit and it just really made me very uh skeptical as to why they were laughing because it's just such a life-threatening situation now on top of that this these rogue waves and giant seas might also lead to major ship destruction so here you can see the bow of the ship has actually been bent down this was not bent down when they first went out and you can see here's a six foot tall person probably between five and six so this ship here is i don't know maybe one two three four five six seven eight nine ten maybe 10 of those people like 60 feet tall so this ship here is is a very tall ship and you must have had giant waves crash on the top of this and here's that idea of a road wave okay so how do road waves occur they occur when big c's uh big waves are moving in opposite directions of a current and then double up you could see this if you go down to say ponto or cardiff or anywhere in carlsbad so all the places where there's an outflow from a lagoon right like santaliho lagoon at cardiff or bataquitos lagoon at ponto ponto is a great spot to see it time the outgoing tide you go down there and if you watch the outgoing tide if you look where the tide is flowing out and the waves are coming in you'll notice that waves are much bigger right where the tide is moving out and and the waves are moving in and then to each side of that rip current which we're going to talk about next chapter or two chapters from now actually you'll see that there's larger waves right in the middle right where that outflow of current is and much smaller waves on either side of that outflowing current so it's a perfect example and uh i hope that one day uh you'll be down at the beach and see that and go oh my gosh i can't believe that he was right you know and surfers know this so more things that surfers know that maybe they don't necessarily know the right name for it's a perfect analog for rogue waves if you're surfing in an outgoing current all right