The equator receives more sunlight than anywhere else on Earth, and this is why it's the warmest part of our planet. Now to understand why, we need to look at how the sun's rays hit the Earth. But for our purposes right now, I want you to pretend that the equator is just this red line I'm drawing through the planet. We'll, in a moment, get to why the image has the Earth tilted and what's important about that. But for now, I want you to pretend that the equator is just level with the lines of the sun's rays. So the sun's rays that hit the Earth more or less straight on, they're coming in more or less perpendicular to the Earth's surface, those rays are going to spread their energy over a smaller area than, for example, these rays up here that come in at an angle to the Earth's surface. Because of that angle, these rays up top are going to spread out over a larger area, whereas these rays by the equator are going to be concentrated in a smaller area. So let's just assume it's the same amount of energy in both regions. You have the same amount of energy in a smaller area versus the same amount of energy in a larger area. Well, in the larger area, you're going to have to spread your energy thinner. That means you're going to have less energy per area, so it's going to be colder. That's why it's colder up at the poles and warmer at the equator. It's due to how the energy from the sunlight is being spread out, and that's due to the angle at which these rays are hitting the Earth.

Now, let's get to the tilt of the Earth in this image. The Earth experiences seasons, you know, and we refer to them as, you know, spring, summer, winter, or fall. Really, what we're talking about though is the tilt of the Earth's axis. This line is what we know as the Earth's axis. It's the axis around which the Earth spins on a daily basis. In this image of the Earth revolving around the sun, you can see these little purple circular arrows. Those are showing the Earth spinning around its axis. The position of this axis relative to the sun changes. So sometimes, like we see in our image, the axis is pointed away from the sun. When the Northern Hemisphere is pointed away from the sun like that, that's what we call winter. That's when the Northern Hemisphere is colder because it's getting even less sunlight than usual. Now, when the Northern Hemisphere points towards the sun, notice that now it's going to be getting more sun rays than the southern hemisphere. That's what we call summer. So the Earth's axis is changing position relative to the Sun as it moves around the Sun, and that's what we experience as seasons. And, hopefully, this little drawing here made it clear that the Northern Hemisphere and the Southern Hemisphere are actually on opposite seasonal schedules, so to speak. You know, we just refer to our northern hemisphere's cold months as winter, but that's actually going to be the hottest time of the year for the southern hemisphere. And likewise, when it's warmest in the Northern Hemisphere, it's going to be colder in the Southern Hemisphere. So, you know, these terms for seasons, fall, winter, spring, and summer are kind of biased towards the Northern Hemisphere. So sorry people in Australia. I'm thinking about you. Now, in addition to the atmosphere circulating, the oceans will also circulate, and this will affect climate patterns, especially those of coastal regions.

Now the oceans circulate all over the planet and we'll talk about that sort of big picture in just a second. But before that, I want to talk a little bit about how coastal regions are affected. To understand that, you need to understand this property of water that we know is specific heat, which is basically the ability of a substance to absorb energy without changing its own temperature. So, what does that mean? If you have a high specific heat, you can absorb a lot of energy and your temperature will only go up a little bit. If you have a low specific heat, your temperature will go up a lot when you absorb a little bit of energy. This is a bit of an oversimplification, but for our purposes, that's all you need to understand. Water has a high specific heat. It can absorb large amounts of energy, and it can also store those large amounts of energy. So around coastal regions, oceans are actually going to be able to warm and cool their coastal areas depending on the relative temperatures of the air in the water. So I'm going to give you an example of this, and we're going to get into some details. You don't really need to understand all the details here. I just want to explain how this is happening. So you can see how these natural forces work together to produce, well, frankly, phenomena that we're pretty familiar with, that we experience on a regular basis. So what happens during the day in a coastal area? Well, during the day, there's the sun out and what's going to happen is the ocean or the water, I should say, is going to absorb more heat than the land, and that's being represented by these red arrows. So that does not mean the air over the ocean or the air over the land. We're talking about the actual ocean and the actual Earth absorbing heat from the sunlight. Now, because the ocean is absorbing more energy, that means the air above the land is actually going to be warmer than the air above the ocean. And that is, again, because the land is not absorbing as much energy as the ocean. The ocean is absorbing lots of energy, meaning the air above it is not absorbing all of that energy, so to speak. So what does this do? Well, if we have hot air, so let's just say, hot air, it's going to rise up. When hot air rises, it's going to leave behind a low pressure pocket. So let's just say low p. So the hot air rises and that leaves us with low pressure. Now, because the air is cooler over the ocean and therefore, denser, we're going to have higher pressure over here, lower pressure over the land. So the air is going to move off the ocean up to the land, also known as a sea breeze. Now, at night, we're basically going to have the opposite scenario play out. The ocean absorbed more energy during the day. So, at night, when things are cooled off, it's going to release more energy. Since it's releasing more energy, that means that the air above the ocean is going to be hotter. So let's do the same thing, hot air, it's going to rise. Now, the land didn't absorb as much energy during the day, meaning it's going to release less heat at night, so it's not going to be, the air above the land is not going to be as warm. It's going to be cooler and it's going to be denser. So we're going to have higher pressure on land. Because the hot air over the ocean is going to rise, we're going to have lower pressure over the ocean, which means we're going to have a breeze moving from the land out to sea. Now you really don't need to worry about memorizing all the intricacies of these processes. I'm just explaining all the steps so you can see how, you know, things as simple as energy will cause all of these, you know, patterns in climate and weather that we experience on a daily basis, or some of us do, I don't know if you live by the ocean or not. I shouldn't say that. I live by the ocean, so I experience these regularly.

Now let's talk about those big picture ocean currents. Right? You know, here we're looking at a small microcosm of what's going on. But as you can see in this image, I mean, the ocean currents are moving all over the planet, and they carry warm and cool water to various regions. For example, here in the Pacific, we have a warm current that moves up along the coast of Asia here, and it's actually going to come across the Pacific and move down the coast of California. That's why the Pacific Ocean in California, despite Southern California's warm temperatures, is always cold. Even in the summer, it's always cold. I grew up on the East Coast and we have that nice warm water that comes up the coast of the Eastern Coast of the United States. But notice how across the Atlantic, they actually have a cold current moving down the coast of Africa there. And you can see this pattern repeated in other currents across the globe. But the point is, these are not static systems. They're dynamic. They're flowing. There's energy moving through them, and that is affecting climate. So with that, let's go ahead and flip the page.