so what that means is if you were down at the beach say at 12 noon right you're at the beach you notice it's a low tide you would know that if you showed up the next day roughly 50 minutes later okay about 50 minutes later you would see another low tide okay so the tide would be roughly the same 50 minutes later the next day it's a slightly um slightly delayed process so the rotation of the earth and the moon's orbit around us makes the full cycle repeat every 24 hours and 50 minutes here's a perfect example so see how the moon is starting to rotate around us as it's rotating it's moving right moving around this is the 24 hour period right straight up at the very top of this again there's 24 hours but it has to go that extra 50 minutes right so it started here watch this blue line you can see that the tide rising and falling and stop 24 24 50 to get back to the moon notice the tide's going down and then once it's lined up again high tide here's another low tide right here and then right 24.50 okay so take a look at this make sense of this okay the fact that the moon is orbiting around earth creates this extra lag time we talked about this a little bit on how things were working earlier with that lag time because the earth is orbiting the sun and the moon phases right we talked about that so now we're talking about this tidal lag which makes it repeat every 24 hours and 50 minutes so something i will ask you once again like i just talked about is that if you're at the beach now say it's three o'clock in the afternoon you notice that it's a high tide um and the very next day you want to go see that high tide again because you want to go fishing all right well the next day if you wanted to go do that you don't need to look at a height you don't need to look at a tide chart you just know okay 50 minutes from then so the next day at 350 is going to be the same tide that i was dealing with the day before roughly speaking okay the tide would be a little bit different but pretty much the same so there you go there you have it now do you need a tide chart after all this stuff to figure out what the tides are going to be no once you're done with these lectures all you're going to need is the moon okay so let's check it out some more now the sun right here's another factor we've only talked about the moon and you kind of get that now right but we got to talk about the sun too because it also produces tights they're just not as big because of this r factor again okay so here's that equation again this r is so much bigger right the distance between the earth and the sun is so much larger that it makes this f much smaller right remember five over one is five but five over a million is a very very small number right like point zero zero zero zero zero zero zero one something right very very small so if this number gets big which it is with the sun then this gets much smaller okay so m1 would be the earth m2 would be the sun g is a constant r is the distance between their centers it's going to be much smaller so it's less significant okay so let's talk about that a little bit here's your equation again m1 m2 and then r squared now look at this here's the earth here's the moon right and this is kind of what we've been talking about and you can see that the moon would have a major effect on earth and you'd think because of m1 and m2 that hey you know what the sun might actually be more useful and change the tides on earth even more but the thing is is that yes it's much more massive than the moon but once again this r factor is squared making it much less significant the fact that r is squared makes it much less significant so look at the uh this is like a representation right but if you look down here this is the actual distance right this is an actual reputation here's the sun you gotta go all the way over here to hit the earth and then the moon is actually much closer right so this is what it actually looks like to scale this is just a representation so let's take a look at this what you want to get from this equation right here right is that as the mass increases right the force increases meaning all right well between the earth and the moon the mass is is is large and the force should go up but if you put the sun in there instead of the moon you'd think that the force should definitely go up right all right that's true but let's look at the bottom side of the equation as the distance goes up so that r the distance between the earth and the moon or the earth and the sun now your distance goes goes through the roof right when you look at the sun then the force goes down but it actually goes mega down right double down it goes double down because r is squared okay so 10 squared is a 100 right it's squared it makes it much larger factor in this equation all these math equations really are is just a story and this is the story it's telling you as the mass goes up the force of gravity goes up but as the distance goes up the force of gravity goes really down therefore the sun has less of an effect on our tides on earth than the moon does that's the overall message the moon has greater influence on the tides than the sun all because this r factor is squared so don't be afraid of math right math is super useful if you can read these equations and you can understand this you're going to do so well in life right it's not just about times okay this class isn't just about oceanography it's about getting you to a place where you can think critically and understand equations like this that make the general public kind of freaked out yet if you can understand them and this is your chance here come ask me questions if you don't get it i'd be i'd love to go over it with you if you can get this stuff then you're not going to be um just so baffled by math and so um kind of freaked out by it to where you feel overwhelmed and you can't deal with it right i want you to be able to deal with math i want you to be able to deal with little curveballs that come along in life okay so math it's very useful i want you to use it remember this whole slide here because i will ask you about this equation as well as why the moon has a greater influence on tides on earth than the sun does even though the sun is so much larger it's all because of that r squared factor and this distance okay now it does affect it a little bit right the sun does affect a little bit so how does this work the highest high tides and the lowest low tides happen when the moon and the sun and the earth are all aligned okay when that occurs if you look back in our lecture before what you'll find is that if the moon were to say be right here okay and you were standing here you'd look out at the moon and if the moon were here in between the earth and the sun it would be a new moon and if the moon were over here it would be a full moon and you can see that oh the moon the earth and the sun are all in a line if they're all in a line you're having high high tides and low low tides because this bulge gets exaggerated on the earth this tidal bulge once again not to scale this is just to get you to understand right but if the moon were to be up here it actually have much less of an effect so let's see how that works all right check it out there we go we got the moon here and here this would be a new moon this would be a full moon therefore you know the tides are going to be extreme they're going to be really high and really low throughout your day that is called spring tides spring tides okay it doesn't just happen in the spring by the way this is just saying spring tides occur when the earth the moon and the sun are all aligned okay now what's the other version look like okay the other version looks like this so tides are not nearly as extreme when the moon and sun are at right angles to each other okay so when they're not aligned so therefore if the moon is here or here we actually have much less of a tidal bulge do you see that you see how it's much less that's because the the earth the gravity from the moon right that's exerting onto the earth is pulling this way and then this gravity from the sun is pulling this way and therefore canceling out the bulge right so if you look at this tidal bulge you can see it's huge tidal bulge right because everything's lined up and they're adding to each other the moon's gravitational pull is adding to the sun's gravitational pull everything's adding right where here everything is subtracting right so it's pulling this way and getting pulled this way therefore you get less of a tidal bulge less extreme what is that called neap tides and this is during first quarter which would be this moon or last quarter which would be this moon that's when you look up in the sky and you can only see half of the moon kind of lit up right that's first or last quarter phases you're going to have an assignment that's to do with this so make sure you check out that assignment let me know if you got questions all right so now you know if you look up into the sky and you see first quarter last quarter moon you're gonna go oh the tides are not very extreme meaning there's not super high tides or super low tides there's kind of medium high tides and medium low tides whereas here you're going to end up with extremely high tides and extremely low tides if you see a new moon or a full moon remember spring tides do not just happen in the spring they happen all year round okay spring tides neap tides make sure you know the difference now this is just a thought for you about um what you would be doing um something that i love to do is go down to the beach and uh check out all the tide pools right and if you haven't done this you really should because you get to see such cool stuff you get to see all sorts of life at low tide way down at the beach hanging out doing your thing seeing starfish seeing seeing enemies seeing fish within little tide pools all sorts of life down there you gotta go check it out if you haven't so you can do a hobby called tide pooling right i do this as i go out go surfing i walk by i see all the creatures i'm just it's it's amazing you got to do it so tide pools they're best exposed when the water levels are very low so when would be the best time to go now that you have those thoughts in your mind about spring tides and neap tides right when would it be would it be a neap tide when the tides are less extreme spring tide when the tides are more extreme or a quarter moon huh well in the way i would explain this i'd start crossing things off process of elimination right with these uh multiple choice questions right what is quarterman quarter moon is the same as a neap tide because first quarter or last quarter that's when a neat tide occurs let's take a look at it again check it out neap tides this is when first quarter or last quarter moons are so therefore the tides are less extreme when that's happening all right well i probably want to go when the when the water levels are very very low right to be able to see as many things as i can so therefore quarter moon neep tide those are the same that's not what i want because i want really low tides i'll use spring tide spring tides b that's your answer okay there you go perfect hopefully that's what you were thinking too you go for the spring tide low tide right you'd wait for that time during the day when the lows were very low