Understanding Earth's Atmosphere and Seasons

Now, chapter one was introduction to the atmosphere, the basic gases, what's around the earth, how do we look at different spheres, and what's happening above the earth, those different layers, the stratosphere, the troposphere, the tropopause, what is the warmest layer, what's the coldest layer. So again, go back and look at chapter one so you can get familiar with some of the questions that may be on test one. Chapter two is about heating the earth's surface and the atmosphere. So how do we warm things up at the ground? How do we warm things up above the ground? And that's what we're going to be looking at in Chapter 2. And all this heat generally is produced by the sun. So first, the earth has two different types of principles. One is rotation. One is revolution. Rotation is the spinning of the earth at its axis. And don't forget, it's tilted at 23 and a half degrees. Revolution refers to the movement of the earth in its orbit around the sun. Remember, the earth goes around the sun. So with that tilt and in a way the sun... um sits in the the universe and the way the earth goes around that's how we start to develop our seasons and also it determines on how much daylight we get on the earth different spots where's the sun uh where's the earth relationship sun going throughout the year so the two most important features for the variation in solar energy reaching particular location the seasonal changes in the angle at which the sun rays strike the earth which in the northern hemisphere that is towards summer, which is June 21st, 22nd, that time frame, and then the length of daylight. So you'll notice that when we talk about this chapter, and also even now currently, that during the summer our sun set around 830. Now the sun is starting to set on Long Island at around 7 to 702. So that's one thing you need to take note of. The less daylight, the less energy, the cooler we're going to be. During the winter, we only get around nine and a half hours of daylight. During the summer... we get about 15 and a half hours of daylight. So there's a big variation. That's why the summer is warmer than the winter. So we're going to be looking at these seasonal changes and also the length of daylight. So the four days throughout the year that's really important to us that everyone looks forward to is the summer solstice, which is in June. Okay, the autumnal equinox or fall, which comes up in September, which is actually coming up next week. Then we have the winter solstice, which is in December. right around December 20th to 22nd, and also the Vernal Equinox, which is coming up in March of next year, roughly around March 19th to the 22nd. It does vary sometimes year to year, and one of the reasons for that is when we talk about the timing, is that it's based on Greenwich Mean Time in Europe, and we're, you know, four to five hours behind them, so if it occurs at, you know, 1 a.m. Greenwich Mean Time, our season will be on a different day here in the United States. So we're going to be looking at where the sun's direct rays hit during our seasonal times, summer, winter, spring, and fall. All right, so some very important pages you need to look at. The smart figures on page 29 through 34, figures 2.2, 2.5, 2.6, 2.9, and basically they look like this. They're going to show you where the sun's rays are hitting. So when you're looking at this, one of the important things you want to notice is right here for December, the sun's direct rays are hitting down here. During our summer, the sun's direct rays are hitting here. So that's one of the things that kind of determines the season, when we're going to be warm, okay? And you can see the revolution, okay, and the rotation going around, how we have a tilt and how the earth is moving around the sun. So you're going to be looking at these key points here, these dates, and where is the sun's direct rays hitting, okay? You can see these different white lines on the Earth. Those are latitude lines. And those latitude lines that we're going to look at, the Tropic of Cancer, the equator, and the Tropic of Capricorn. So those are the things we have to look at when we're looking at different seasons. Because where the sun's rays are hitting on the Earth, we'll get a very good idea on what season it is. So notice the tilt of the Earth and the location of the sun's rays hitting the Earth. Okay, so let's take a look at this. In June. So we're past June now, but notice up here where Long Island is, it says roughly about 15 hours of daylight. That's because when we're in our summer solstice, the sun's direct rays are hitting this line right here, 23.5 degrees north. So the sun's direct rays are hitting the Tropic of Cancer around June 20th, 21st, and 22nd. As opposed to during the winter solstice, okay. this is northern hemisphere the sun's direct rays are hitting down here which is around 23 and a half degrees south So you can see in the northern hemisphere we're around nine hours near Long Island. So different seasons will give us different hours. Then in spring and fall, the equinox means equal. So we get 12 hours of daylight, 12 hours of darkness. Okay, so those are the things we really need to pay attention to where the sun's direct rays are going to hit on the earth. So some of the important ones are right here. Tropic of Cancer, the equator, and Tropic of Capricorn. So when we look at these weather maps, look where the sun's direct rays are hitting. So let's get the naming of some of these. Okay. First, at 23.5 degrees north, this is known as the Tropic of Cancer. The Tropic of Cancer is at 23.5 degrees north. The equator is at zero. The Tropic of Capricorn is at 23.5 degrees south. Tropic of Cancer is 23.5 degrees north. These three lines are going to be very important to understand what season we are in. Okay. And you can see how this is split. Half the earth is lit. Half the earth is dark. That's what we mean by the equinox. Equal daylight, equal darkness. And that is 12 hours. So that circle of illumination goes right through the North Pole where half the earth is dark and half the earth is lit. So we're going to be focusing on where are these sun's rays hitting during what time of the year. So let's start out with spring and fall. Okay. During spring and fall, March and September, the sun's direct rays will hit the equator. Okay. And that is allowing us to have unilateral 12 hours of daylight and 12 hours of darkness. So during spring and fall, okay, the autumnal equinox or fall equinox, the vernal equinox or spring equinox. The sun's direct rays hit the equator. We get 12 hours of daylight, 12 hours of darkness. By the way, Farmingdale is roughly latitude line around 40 degrees north. Okay, so these are the latitude lines, 40 degrees north, 23.5 degrees south, 0, 23.5 degrees north, 0, 23.5 degrees south, 40 degrees south. You have the Arctic Circle at 66.5 degrees north, and you have the Antarctic Circle, which is down at 66.5 degrees south. So let's look at summer. The sun's direct rays are hitting into the northern hemisphere. OK, so that's why we have longer days in our summer or in when the sun's direct rays are hitting the northern hemisphere. So right here are 23 and a half degrees north. This is the Tropic of Cancer. The sun's rays are hitting here. Long Island is roughly around 40 degrees north. So during June, we get about 15 hours of daylight, where our sun will rise at around 525 in the morning, and our sun will set roughly at around 825 in the evening. Now, when we're in our summer, okay, this is the northern hemisphere summer, the North Pole gets about 24 hours of daylight, the South Pole gets zero. So this is very important to understand. So if you've ever been to Miami, okay, or through Texas, you've ever been to Miami, you've ever been to the North Pole, the sun actually sets later the further north you go in the summer. So around Maine, they get about 16 to 17 hours, Long Island 15. But down towards Miami, they're only getting about 13 and a half to 14 hours in the summer. Now that's kind of reversed as we go into the winter. So as we head into the winter, you can see now where the sun's direct rays are hitting. So now they're hitting in the southern hemisphere. So right along 23 and a half degrees south, which is right here, this is the Tropic of Capricorn. Long Island, which is up around 40 degrees north, is roughly getting around nine hours. So our winter solstice, December, is when we have our shortest daylight hours. Notice the North Pole is now dark. The South Pole is now lit, 24 hours. So you can see how we have decreasing sunshine from south to north, from the southern hemisphere to northern hemisphere. And during the winter solstice, which is roughly around December 20th, 21st, and 22nd, the sun's direct rays are hitting the Tropic of Cancer. I'm sorry, Tropic of Capricorn. Tropic of Capricorn is 23.5 degrees south. Tropic of Cancer is 23.5 degrees north. So when the sun's rays hit Tropic of Cancer, which is 23.5 degrees north, that is our summer. When the sun's direct rays are hitting 23.5 degrees south, that is our winter. And when the sun's direct rays are hitting... Zero or the equator that is our spring or fall so understand where the sun's direct rays are hitting during what time of the year Right now we are approaching our equinox and the sun's rays Okay are generally just north of the equator right now. Okay, we're roughly around two to three degrees north Okay, sunrise for today is roughly around 630, sunsets roughly around 7 p.m. So we're getting real close to that equinox. So right now during your class, we're going to get close to the winter solstice, but we're going to go from summer solstice to the fall equinox or the autumnal equinox, and we'll get real close to this point come late in our semester. So by the time we get towards December, when you're taking your final, your sun will set between 4 30 and 5 p.m. So understand where the sun's direct rays are hitting during certain times of the year. You can see as we go back here, right now our orbit around the sun is allowing, we're tilting slightly still towards the sun in the northern hemisphere. The sun's direct rays are approaching the equator, so that will give us 12 hours of daylight, 12 hours of darkness. And that circle of illumination is right through the poles. Now, as we go towards December, you can see as we tilt away in the northern hemisphere, we're getting less daylight and less energy. So as we're tilted towards more energy, more daylight, summer is warmer. Tilted away, less energy, less daylight, colder conditions. And those seasons will change as the Earth goes around the sun and the tilt changes. So our warmest time of the year, most daylight, most energy is summer. Least amount of energy, least amount of sun is towards our winter. Okay, so those are what we're going to be looking at. Understand where the Tropic of Cancer is, the equator, and the Tropic of Capricorn. So again, you can see there's going to be a couple different diagrams here of how the Earth goes around the sun, how the sun is tilted towards the Earth, and that'll give us an idea of what season we're in. So you can see September, spring south of the equator, fall north of the equator. Sun shines equally on the southern and northern equator once we're at the equinox. Daylight, 12 hours. Nighttime, 12 hours. Understanding the sun angle, you're not going to have to know how to calculate this for the test, but just getting an idea. During the summer, okay, our noon sun angle is roughly around 73.5 degrees. So that's a lot of energy hitting the Earth. We never get a full 90 degree angle. That happens at 23 and a half degrees south. So we never get full incoming solar radiation from the sun. So in our summer, our highest sun angle will give us the most energy. And then notice in our winter, roughly around December 21st, our noon sun angle is around 23 and a half degrees south where the sun's hitting. So when you add all that in, the noon sun angle in winter is 26.5 degrees. So you go from a high angle, high energy, a lot of incoming energy from the sun to a very small energy. That's why we're so cold in the winter. And that's why we're so warm in the summer. So again, understand the latitude lines, what it represents the Tropic of Cancer, the equator and Tropic of Capricorn. And just a reminder, the sun's direct rays hitting the Tropic of Cancer when we're in our summer in the northern hemisphere, in our equator during our March and spring. March, spring, and fall in September, and Tropic of Capricorn, 23.5 degrees south, when we are in our winter. Now, the seasons are opposite from the northern hemisphere to the southern hemisphere. So if we're in summer, southern hemisphere is in winter. If we're in fall, southern hemisphere is in spring. So we have opposite seasons. So there's a lot more diagrams here. And again, these are the same diagrams are on page 29 through 34. So make sure you take a look at the diagrams in the book, and obviously they are here in the notes as well. Here's our almanacs to give you an idea of when we're looking at the information of when the sun will set, what the record should be. By the way, daylight saving time goes through November 1st. After that, we fall back. We turn the clocks back, and that's one of the reasons why the sun sets roughly around 425 in December. Our fall officially begins September 22nd at 9.31 in the morning, Eastern Daylight Time. Winter will begin Monday, December 21st at 5.02 a.m. Eastern Standard Time. So we have the clocks that move forward and backwards. So how do we know when the seasons actually start? When the sun's direct rays hit that location, 23.5 degrees north, Tropic of Cancer, the equator, and 23.5 degrees south, Tropic of Capricorn. What the time is at Greenwich Mean Time, that's what time it is. And we're roughly about four to five hours behind that time frame. So... The sun's direct rays are hitting the earth and we can pinpoint when the actual season will start. Now in weather terms, meteorological seasons are a little bit different. They're broken down into three months so we can get better averages and they represent more when it's actually warm, cold, or kind of cool or mild. So fall for meteorologists or meteorological start was September 1st and that goes September, October, November. December 1st is when winter starts for meteorological. situations. Astronomical is when the sun's direct rays hit a certain portion of the earth. And again, our fall will start Tuesday, September 22nd at 9.31 a.m. That's when the sun's direct rays are hitting the equator. Our winter, Monday, December 21st at 5.02 a.m. That's when the sun's direct rays will hit the Tropic of Capricorn, which is 23.5 degrees south. And as we go back towards next summer, roughly around June 20th, that's when the sun's rays will hit. Tropic of Cancer at 23.5 degrees north. So you can read more about why the seasons change to follow up with what I just went over, understanding where the sun's direct rays are hitting during a certain time of year. Now, as the sun's rays come in and we're tilted towards the sun, we get a lot more energy coming in. So what is energy? Energy is the ability to do work. There are two major categories of energy. One is kinetic energy and one is potential energy. So kinetic energy is thought to be the energy of motion. Things are moving around the atmosphere. Think about little, if you've ever seen a little ball pit that kids play in, all the balls are moving around. That is kinetic energy. The molecules in the atmosphere, those are kinetic energy. They're moving all around, okay? Potential energy is the ability to do work, okay? That I'm sitting here right now doing nothing, but if I get up and start talking and moving, that would be kinetic energy. In the atmosphere... Water droplets suspended in a cloud that's not falling from the sky, that's potential energy. Little water droplets hanging out in the cloud suspended there, that's potential. And then as it actually starts to rain, that's the kinetic energy. And when there's a lot of kinetic energy, we get thunderstorms and we can get tornadoes, we can get hurricanes. So those are the differences between potential, which is the ability to do something. Kinetic is the actual movement of all the little motions and molecules in the atmosphere. So there's a heat transfer. Heat is the transfer of energy, okay, into and out of an object because of temperature difference between that object and its surroundings. Go read to follow up again on page 35 to 38. So basically what we're going to be doing is how is heat going from one object to another, okay? And this is one a lot of people are familiar with because you can kind of touch it. Conduction. If you ever boiled water, if you ever cooked pasta, okay, and you have a metal handle and you're cooking that pasta, you turn the flames on high if you go to touch that metal handle you're going to burn yourself that's conduction that's why we have mittens or if you ever put a metal spoon into boiling water it's going to move from that water into that metal spoon metal spoon is going to get hot if you touch it you're going to get burn yourself convection see those little water molecules moving up and down that's in the atmosphere as well the movement of air upward and downward is convection convection, air going upward and downward. So when you boil water, that's convection. That's how the atmosphere is working. You heat the ground and the air rises. So convection is when you boil water or in the atmosphere, heat rises and the air molecules go up and down. There's another word, advection, which is not part of the three mechanisms of heat transfer. Advection, not part of the three mechanisms of heat transfer, but it's the horizontal movement. of energy or heat okay advection is horizontal not part of three mechanisms the main mechanisms but you have convection which is vertical horizontally is advection so convection conduction and then we have radiation that's the energy that's coming in from the sun or you can see here flames off of a fire pit maybe logs or your stove that's radiation all objects give off some sort of radiation And radiation can be very deadly depending on what type of radiation. For example, an x-ray is dangerous radiation. If you get enough x-rays, that radiation can make your bones a little brittle. So three mechanisms of heat transfer. Conduction, a transfer of heat through matter by molecular motion, activity or motion. So it's going to go from one object to another. Convection, a transfer of heat by mass movement or circulation within a substance. Air going up and down or water bubbles going up and down. Radiation, a transfer mechanism by which solar energy reaches the planet. That's the sun's rays coming in. into our atmosphere. That's what's going to heat us. So if we don't have the sun, we're looking at much cooler conditions, a much cooler climate. So that's why in our summer, as we're facing towards the sun, we're warmer in the northern hemisphere. So if we got rid of the sun, we have more darkness and we would be much, much cooler. So we're going to understand radiation, okay? I'm going to end the video here. Please look at chapter one, chapter two, go over the first part. understand the seasons. If you have any questions, let me know.

How do we warm things up above the ground? And that's what we're going to be looking at in Chapter 2. And all this heat generally is produced by the sun. So first, the earth has two different types of principles.

One is rotation. One is revolution. Rotation is the spinning of the earth at its axis. And don't forget, it's tilted at 23 and a half degrees. Revolution refers to the movement of the earth in its orbit around the sun.

Remember, the earth goes around the sun. So with that tilt and in a way the sun... um sits in the the universe and the way the earth goes around that's how we start to develop our seasons and also it determines on how much daylight we get on the earth different spots where's the sun uh where's the earth relationship sun going throughout the year so the two most important features for the variation in solar energy reaching particular location the seasonal changes in the angle at which the sun rays strike the earth which in the northern hemisphere that is towards summer, which is June 21st, 22nd, that time frame, and then the length of daylight.

So you'll notice that when we talk about this chapter, and also even now currently, that during the summer our sun set around 830. Now the sun is starting to set on Long Island at around 7 to 702. So that's one thing you need to take note of. The less daylight, the less energy, the cooler we're going to be. During the winter, we only get around nine and a half hours of daylight. During the summer...

we get about 15 and a half hours of daylight. So there's a big variation. That's why the summer is warmer than the winter.

So we're going to be looking at these seasonal changes and also the length of daylight. So the four days throughout the year that's really important to us that everyone looks forward to is the summer solstice, which is in June. Okay, the autumnal equinox or fall, which comes up in September, which is actually coming up next week. Then we have the winter solstice, which is in December. right around December 20th to 22nd, and also the Vernal Equinox, which is coming up in March of next year, roughly around March 19th to the 22nd.

It does vary sometimes year to year, and one of the reasons for that is when we talk about the timing, is that it's based on Greenwich Mean Time in Europe, and we're, you know, four to five hours behind them, so if it occurs at, you know, 1 a.m. Greenwich Mean Time, our season will be on a different day here in the United States. So we're going to be looking at where the sun's direct rays hit during our seasonal times, summer, winter, spring, and fall.

All right, so some very important pages you need to look at. The smart figures on page 29 through 34, figures 2.2, 2.5, 2.6, 2.9, and basically they look like this. They're going to show you where the sun's rays are hitting.

So when you're looking at this, one of the important things you want to notice is right here for December, the sun's direct rays are hitting down here. During our summer, the sun's direct rays are hitting here. So that's one of the things that kind of determines the season, when we're going to be warm, okay?

And you can see the revolution, okay, and the rotation going around, how we have a tilt and how the earth is moving around the sun. So you're going to be looking at these key points here, these dates, and where is the sun's direct rays hitting, okay? You can see these different white lines on the Earth. Those are latitude lines. And those latitude lines that we're going to look at, the Tropic of Cancer, the equator, and the Tropic of Capricorn.

So those are the things we have to look at when we're looking at different seasons. Because where the sun's rays are hitting on the Earth, we'll get a very good idea on what season it is. So notice the tilt of the Earth and the location of the sun's rays hitting the Earth.

Okay, so let's take a look at this. In June. So we're past June now, but notice up here where Long Island is, it says roughly about 15 hours of daylight. That's because when we're in our summer solstice, the sun's direct rays are hitting this line right here, 23.5 degrees north. So the sun's direct rays are hitting the Tropic of Cancer around June 20th, 21st, and 22nd.

As opposed to during the winter solstice, okay. this is northern hemisphere the sun's direct rays are hitting down here which is around 23 and a half degrees south So you can see in the northern hemisphere we're around nine hours near Long Island. So different seasons will give us different hours. Then in spring and fall, the equinox means equal. So we get 12 hours of daylight, 12 hours of darkness.

Okay, so those are the things we really need to pay attention to where the sun's direct rays are going to hit on the earth. So some of the important ones are right here. Tropic of Cancer, the equator, and Tropic of Capricorn.

So when we look at these weather maps, look where the sun's direct rays are hitting. So let's get the naming of some of these. Okay.

First, at 23.5 degrees north, this is known as the Tropic of Cancer. The Tropic of Cancer is at 23.5 degrees north. The equator is at zero. The Tropic of Capricorn is at 23.5 degrees south. Tropic of Cancer is 23.5 degrees north.

These three lines are going to be very important to understand what season we are in. Okay. And you can see how this is split. Half the earth is lit. Half the earth is dark.

That's what we mean by the equinox. Equal daylight, equal darkness. And that is 12 hours. So that circle of illumination goes right through the North Pole where half the earth is dark and half the earth is lit.

So we're going to be focusing on where are these sun's rays hitting during what time of the year. So let's start out with spring and fall. Okay. During spring and fall, March and September, the sun's direct rays will hit the equator. Okay.

And that is allowing us to have unilateral 12 hours of daylight and 12 hours of darkness. So during spring and fall, okay, the autumnal equinox or fall equinox, the vernal equinox or spring equinox. The sun's direct rays hit the equator. We get 12 hours of daylight, 12 hours of darkness. By the way, Farmingdale is roughly latitude line around 40 degrees north.

Okay, so these are the latitude lines, 40 degrees north, 23.5 degrees south, 0, 23.5 degrees north, 0, 23.5 degrees south, 40 degrees south. You have the Arctic Circle at 66.5 degrees north, and you have the Antarctic Circle, which is down at 66.5 degrees south. So let's look at summer. The sun's direct rays are hitting into the northern hemisphere.

OK, so that's why we have longer days in our summer or in when the sun's direct rays are hitting the northern hemisphere. So right here are 23 and a half degrees north. This is the Tropic of Cancer. The sun's rays are hitting here. Long Island is roughly around 40 degrees north.

So during June, we get about 15 hours of daylight, where our sun will rise at around 525 in the morning, and our sun will set roughly at around 825 in the evening. Now, when we're in our summer, okay, this is the northern hemisphere summer, the North Pole gets about 24 hours of daylight, the South Pole gets zero. So this is very important to understand. So if you've ever been to Miami, okay, or through Texas, you've ever been to Miami, you've ever been to the North Pole, the sun actually sets later the further north you go in the summer. So around Maine, they get about 16 to 17 hours, Long Island 15. But down towards Miami, they're only getting about 13 and a half to 14 hours in the summer.

Now that's kind of reversed as we go into the winter. So as we head into the winter, you can see now where the sun's direct rays are hitting. So now they're hitting in the southern hemisphere.

So right along 23 and a half degrees south, which is right here, this is the Tropic of Capricorn. Long Island, which is up around 40 degrees north, is roughly getting around nine hours. So our winter solstice, December, is when we have our shortest daylight hours.

Notice the North Pole is now dark. The South Pole is now lit, 24 hours. So you can see how we have decreasing sunshine from south to north, from the southern hemisphere to northern hemisphere. And during the winter solstice, which is roughly around December 20th, 21st, and 22nd, the sun's direct rays are hitting the Tropic of Cancer.

I'm sorry, Tropic of Capricorn. Tropic of Capricorn is 23.5 degrees south. Tropic of Cancer is 23.5 degrees north. So when the sun's rays hit Tropic of Cancer, which is 23.5 degrees north, that is our summer. When the sun's direct rays are hitting 23.5 degrees south, that is our winter.

And when the sun's direct rays are hitting... Zero or the equator that is our spring or fall so understand where the sun's direct rays are hitting during what time of the year Right now we are approaching our equinox and the sun's rays Okay are generally just north of the equator right now. Okay, we're roughly around two to three degrees north Okay, sunrise for today is roughly around 630, sunsets roughly around 7 p.m.

So we're getting real close to that equinox. So right now during your class, we're going to get close to the winter solstice, but we're going to go from summer solstice to the fall equinox or the autumnal equinox, and we'll get real close to this point come late in our semester. So by the time we get towards December, when you're taking your final, your sun will set between 4 30 and 5 p.m.

So understand where the sun's direct rays are hitting during certain times of the year. You can see as we go back here, right now our orbit around the sun is allowing, we're tilting slightly still towards the sun in the northern hemisphere. The sun's direct rays are approaching the equator, so that will give us 12 hours of daylight, 12 hours of darkness. And that circle of illumination is right through the poles. Now, as we go towards December, you can see as we tilt away in the northern hemisphere, we're getting less daylight and less energy.

So as we're tilted towards more energy, more daylight, summer is warmer. Tilted away, less energy, less daylight, colder conditions. And those seasons will change as the Earth goes around the sun and the tilt changes.

So our warmest time of the year, most daylight, most energy is summer. Least amount of energy, least amount of sun is towards our winter. Okay, so those are what we're going to be looking at. Understand where the Tropic of Cancer is, the equator, and the Tropic of Capricorn.

So again, you can see there's going to be a couple different diagrams here of how the Earth goes around the sun, how the sun is tilted towards the Earth, and that'll give us an idea of what season we're in. So you can see September, spring south of the equator, fall north of the equator. Sun shines equally on the southern and northern equator once we're at the equinox. Daylight, 12 hours.

Nighttime, 12 hours. Understanding the sun angle, you're not going to have to know how to calculate this for the test, but just getting an idea. During the summer, okay, our noon sun angle is roughly around 73.5 degrees. So that's a lot of energy hitting the Earth.

We never get a full 90 degree angle. That happens at 23 and a half degrees south. So we never get full incoming solar radiation from the sun.

So in our summer, our highest sun angle will give us the most energy. And then notice in our winter, roughly around December 21st, our noon sun angle is around 23 and a half degrees south where the sun's hitting. So when you add all that in, the noon sun angle in winter is 26.5 degrees. So you go from a high angle, high energy, a lot of incoming energy from the sun to a very small energy.

That's why we're so cold in the winter. And that's why we're so warm in the summer. So again, understand the latitude lines, what it represents the Tropic of Cancer, the equator and Tropic of Capricorn. And just a reminder, the sun's direct rays hitting the Tropic of Cancer when we're in our summer in the northern hemisphere, in our equator during our March and spring.

March, spring, and fall in September, and Tropic of Capricorn, 23.5 degrees south, when we are in our winter. Now, the seasons are opposite from the northern hemisphere to the southern hemisphere. So if we're in summer, southern hemisphere is in winter.

If we're in fall, southern hemisphere is in spring. So we have opposite seasons. So there's a lot more diagrams here. And again, these are the same diagrams are on page 29 through 34. So make sure you take a look at the diagrams in the book, and obviously they are here in the notes as well.

Here's our almanacs to give you an idea of when we're looking at the information of when the sun will set, what the record should be. By the way, daylight saving time goes through November 1st. After that, we fall back. We turn the clocks back, and that's one of the reasons why the sun sets roughly around 425 in December. Our fall officially begins September 22nd at 9.31 in the morning, Eastern Daylight Time.

Winter will begin Monday, December 21st at 5.02 a.m. Eastern Standard Time. So we have the clocks that move forward and backwards.

So how do we know when the seasons actually start? When the sun's direct rays hit that location, 23.5 degrees north, Tropic of Cancer, the equator, and 23.5 degrees south, Tropic of Capricorn. What the time is at Greenwich Mean Time, that's what time it is.

And we're roughly about four to five hours behind that time frame. So... The sun's direct rays are hitting the earth and we can pinpoint when the actual season will start.

Now in weather terms, meteorological seasons are a little bit different. They're broken down into three months so we can get better averages and they represent more when it's actually warm, cold, or kind of cool or mild. So fall for meteorologists or meteorological start was September 1st and that goes September, October, November.

December 1st is when winter starts for meteorological. situations. Astronomical is when the sun's direct rays hit a certain portion of the earth.

And again, our fall will start Tuesday, September 22nd at 9.31 a.m. That's when the sun's direct rays are hitting the equator. Our winter, Monday, December 21st at 5.02 a.m.

That's when the sun's direct rays will hit the Tropic of Capricorn, which is 23.5 degrees south. And as we go back towards next summer, roughly around June 20th, that's when the sun's rays will hit. Tropic of Cancer at 23.5 degrees north.

So you can read more about why the seasons change to follow up with what I just went over, understanding where the sun's direct rays are hitting during a certain time of year. Now, as the sun's rays come in and we're tilted towards the sun, we get a lot more energy coming in. So what is energy?

Energy is the ability to do work. There are two major categories of energy. One is kinetic energy and one is potential energy. So kinetic energy is thought to be the energy of motion.

Things are moving around the atmosphere. Think about little, if you've ever seen a little ball pit that kids play in, all the balls are moving around. That is kinetic energy. The molecules in the atmosphere, those are kinetic energy.

They're moving all around, okay? Potential energy is the ability to do work, okay? That I'm sitting here right now doing nothing, but if I get up and start talking and moving, that would be kinetic energy. In the atmosphere...

Water droplets suspended in a cloud that's not falling from the sky, that's potential energy. Little water droplets hanging out in the cloud suspended there, that's potential. And then as it actually starts to rain, that's the kinetic energy.

And when there's a lot of kinetic energy, we get thunderstorms and we can get tornadoes, we can get hurricanes. So those are the differences between potential, which is the ability to do something. Kinetic is the actual movement of all the little motions and molecules in the atmosphere.

So there's a heat transfer. Heat is the transfer of energy, okay, into and out of an object because of temperature difference between that object and its surroundings. Go read to follow up again on page 35 to 38. So basically what we're going to be doing is how is heat going from one object to another, okay? And this is one a lot of people are familiar with because you can kind of touch it. Conduction.

If you ever boiled water, if you ever cooked pasta, okay, and you have a metal handle and you're cooking that pasta, you turn the flames on high if you go to touch that metal handle you're going to burn yourself that's conduction that's why we have mittens or if you ever put a metal spoon into boiling water it's going to move from that water into that metal spoon metal spoon is going to get hot if you touch it you're going to get burn yourself convection see those little water molecules moving up and down that's in the atmosphere as well the movement of air upward and downward is convection convection, air going upward and downward. So when you boil water, that's convection. That's how the atmosphere is working. You heat the ground and the air rises.

So convection is when you boil water or in the atmosphere, heat rises and the air molecules go up and down. There's another word, advection, which is not part of the three mechanisms of heat transfer. Advection, not part of the three mechanisms of heat transfer, but it's the horizontal movement.

of energy or heat okay advection is horizontal not part of three mechanisms the main mechanisms but you have convection which is vertical horizontally is advection so convection conduction and then we have radiation that's the energy that's coming in from the sun or you can see here flames off of a fire pit maybe logs or your stove that's radiation all objects give off some sort of radiation And radiation can be very deadly depending on what type of radiation. For example, an x-ray is dangerous radiation. If you get enough x-rays, that radiation can make your bones a little brittle. So three mechanisms of heat transfer. Conduction, a transfer of heat through matter by molecular motion, activity or motion.

So it's going to go from one object to another. Convection, a transfer of heat by mass movement or circulation within a substance. Air going up and down or water bubbles going up and down. Radiation, a transfer mechanism by which solar energy reaches the planet.

That's the sun's rays coming in. into our atmosphere. That's what's going to heat us.

So if we don't have the sun, we're looking at much cooler conditions, a much cooler climate. So that's why in our summer, as we're facing towards the sun, we're warmer in the northern hemisphere. So if we got rid of the sun, we have more darkness and we would be much, much cooler. So we're going to understand radiation, okay?

I'm going to end the video here. Please look at chapter one, chapter two, go over the first part. understand the seasons.

If you have any questions, let me know.

Transcript for:Understanding Earth's Atmosphere and Seasons

Transcript for:
Understanding Earth's Atmosphere and Seasons