Earth's Climate Patterns - Online Tutor, Practice Problems & Exam Prep

Weather refers to short-term atmospheric conditions, while climate is the long-term average of these conditions, impacting biogeography. Sunlight angles vary by latitude, affecting global climate, with maximum heat at the equator. Earth's 23.5-degree axial tilt creates seasons, while the Hadley cell influences air circulation and precipitation patterns, leading to rainforests at the equator and deserts at 30 degrees latitude. The Coriolis effect curves prevailing winds, affecting ocean currents and climate. Water stabilizes nearby land climates due to its high specific heat, while mountains create rain shadows, demonstrating the interconnectedness of climate and life.

Weather vs. Climate

This video, we're going to differentiate between the weather and the climate. The term weather refers to local short-term atmospheric conditions, usually measured over a period of just a few hours or days. The temperature, precipitation, cloud cover, and wind are four key components of the weather. Now, the weather tends to be quite variable and unpredictable even on a short-term basis of just a few hours, where in the morning it could be sunny weather, and in the afternoon it could be quite rainy and stormy weather. On a graph like this one that we can see here that has atmospheric conditions on the y-axis and time on the x-axis on a short-term scale of just a few hours or days, we might expect to see quite a lot of variability and unpredictability.

So we might expect our graph to look something like this, for example. Now, the climate, on the other hand, refers to long-term averages of the weather conditions in a specific region, usually measured over a period of years, decades, or centuries, and therefore, the climate has less variability and more predictable patterns. And that's why our lesson focuses on climate rather than focusing on weather. The climate is also going to be the primary factor impacting biogeography and the distribution of land organisms or terrestrial organisms, and aquatic organisms that live in the water use the water as a barrier to protect it from atmospheric conditions, so they're not impacted as much by them. Now, down below in this image on the right, again, we can see that the climate is on a long-term scale of years or decades, looking at averages.

On a similar graph like this one, notice we have the time on the x-axis on a long-term scale. We might expect to see less variability and more predictability, something like that, for example. This here concludes our lesson, and I'll see you in our next video.

Earth's Climate Patterns Example 1

So here we have an example problem asking, which of the following would be considered an example of climate? And we've got these 4 potential answer options down below. Now option a says, a sudden temperature drop at night in Chicago. Because this is happening suddenly over a short period of time, this is not going to be the best example of climate. In fact, this is an example of weather, so we can go ahead and eliminate answer option a.

Now option b says, the record rainfall received in Houston last week. This is looking at the rainfall over just a period of a week. It's just looking at 7 days, and it's not looking at the average rainfall over periods of years, decades, or centuries. So for that reason, option b is not going to be the best option here. So now we're between either option c or option d.

And notice option d says the severe thunderstorm in Miami this afternoon. Again, this is over a short period of time, just a few hours. And so for that reason, we can eliminate answer option d because that's an example of weather, not climate. Of course, this leaves answer option c as the only option, which is the correct answer. It says the average annual rainfall in Buffalo over 50 years.

Now, this is looking at the long-term average rainfall over many, many years, which is why this is the best example of climate. So we can indicate c here is the correct answer. That concludes this problem, and I'll see you on our next video.

Variation in Sunlight Angles Across Latitudes

In this video, we're going to talk about variation in sunlight angles across latitudes. And so global climate is greatly impacted by the angle at which the sun's rays hit the Earth's surface, which varies across latitudes because the Earth is spherical. Now latitudes are imaginary lines measuring the distance north or south of the equator in degrees, where 0 degrees represents the equator and 90 degrees represents the poles, either the north or south pole. So let's take a quick look at our image down below because we have these very latitudes labeled on the right side. And, again, the equator is the most important latitude that all other latitudes are based on.

It is the midline of the earth, and it separates the earth into the northern and southern hemispheres. Now outside of that, we have the tropic of Cancer and tropic of Capricorn, which appear at 23.5 degrees latitude, and they are important because they define what are known as the tropics, or this tropical region that you can see highlighted here. Now immediately outside of the tropical region, we have the subtropical region, which extends from about 23.5 degrees latitude up to about 35 degrees latitude, and that marks the beginning of the temperate region, which extends from about 35 degrees latitude up to 66.5 degrees latitude. And in the north, we call this the Arctic Circle, and in the south, we call this the Antarctic Circle. So it defines the Arctic and Antarctic regions, which are polar regions where the North Pole and the South Pole can be found.

So make sure to check with your professors which of these latitudes you may be expected to memorize. Now a very important takeaway of this video is that the sun's maximum delivery of heat and energy only occurs when the sun is directly overhead and the sun's rays are hitting the Earth's surface at a 90 degree angle. And this maximum delivery of heat and energy only occurs in regions that are near the equator, and that's going to allow those regions to receive the most direct sunlight angles throughout the year, which is what gives these regions like the tropics relatively hot climate all year round. So notice in the image, we're indicating that the sun is directly overhead giving hot climate here in the tropical regions. And as you move outside of the tropical regions towards the poles in either hemisphere, notice that the sunlight angles get lower and lower, and lower angles of sunlight correspond with colder climates, which is why the poles are associated with cold, climates.

Now another interesting way to look at this image is notice that each of these yellow bars here represents the amount of heat and energy delivered by the sun, and they're all the same height. So they all contain the same amount of heat and energy. However, notice that near the equator, the energy is spread out over a small area, and, therefore, there is a relatively high amount of heat and energy per unit area. But notice that with the lower angles of sunlight, the energy is spread across a larger area, and that means that there's less energy per unit area, and that's also associated with colder climates. So this here concludes our video, and I'll see you all in our next one.

Earth’s Tilted Axis, Orbit, & Seasons

This video, we're going to talk about Earth's tilted axis, its orbit around the sun, and the seasons. And so it turns out that Earth's axis of rotation upon which it spins is actually tilted 23.5 degrees relative to the plane at which the Earth orbits the sun, and this tilt is actually maintained in a constant direction all year long. Now this tilt of the Earth's axis, along with its orbit around the sun, causes variability in Earth's heating all year round, creating the seasons. And the most classic traditional seasons that most of us are familiar with are winter, spring, summer, and fall. Now it's important to note that at any given point in the Earth's orbit around the sun, the northern and southern hemispheres are going to have opposite seasons.

So let's take a look at our image down below so we can understand this a bit better. You can clearly see that Earth's axis of rotation upon which it spins is tilted 23 and a half degrees. And over here on the right, we're showing you 4 different snapshots of Earth's orbit around the sun, and we also got this note that says indicated seasons in this image focus on the northern hemisphere. So notice that in this particular snapshot, the axis is actually tilted towards the sun, and that's going to allow the northern hemisphere to receive more direct angles of sunlight, and that allows the northern hemisphere to experience the summer solstice. Now notice that on the opposite end of the orbit way over here, the direction of Earth's tilted axis is maintained, so it's still pointing towards the top right.

And because that's the case, notice that the northern hemisphere over here in this snapshot is actually tilted away from the sun. And so it's going to receive lower angles of sunlight, and that's going to allow the northern hemisphere to experience the winter solstice or the winter season. Now, of course, the transition from winter to summer is going to go through the spring equinox, and the transition from summer to winter is going to transition through the fall equinox. Now, it is important to keep in mind that, again, the northern hemisphere and the southern hemisphere will have opposite seasons. So when it's the summer solstice in the northern hemisphere, it's actually the winter solstice in the southern hemisphere.

So this here concludes our lesson, and I'll see you all in our next video.

Earth's Climate Patterns Example 2

So here we have an example problem that wants us to choose one of the 4 potential answer options down below that best completes the statement that says seasons are ultimately caused by blank, and option A says the speed of Earth's rotation. Now, the speed of Earth's rotation is not going to be a direct cause of the season. So for that reason, we can eliminate answer option A. If everything was exactly the same but we only changed the speed of Earth's rotation, we would still have the seasons. It's just the seasons might look a little bit different, but we would still have them.

Now option D says ocean currents. And once again, we know that the ocean currents are not a direct cause of the season, so we can eliminate answer option D. So now we're between either option B or option C. And notice option C says the time it takes for the Earth to orbit the sun. Now, the amount of time that it takes for the Earth to orbit the sun is not a direct cause of the season.

If everything was kept exactly the same, but we only changed how long it took for the Earth to make a complete orbit of the sun, we would still have the seasons. It's just that the seasons might be spread across longer periods of time, but we would still have the seasons. So for that reason, we can eliminate answer option C. So this leaves answer option B as the only option and it is the best option for this problem, which says the tilt of the Earth's axis. So recall from our previous lesson videos that the seasons are actually caused by both the tilt of the Earth's axis of rotation and the Earth's orbit around the sun itself.

And so, it's not the time it takes for the Earth to orbit the sun; it's the orbit around the sun itself. And so, option B, again, is going to be the correct answer to this example problem. That concludes this problem, and I'll see you in our next video.

The amount of solar energy & heat delivered to different latitudes on Earth is ultimately determined by:

• A. The spherical shape of the Earth and the angle that solar radiation hits the Earth.
• B. Earth’s slightly elliptical orbit around the Sun.
• C. The tilt of the Earth’s axis with respect to its orbit around the sun.
• D. Ocean currents.

Broad Patterns of Global Air Circulation & Precipitation

This video, we're going to talk about broad patterns of global air circulation and precipitation, mainly focusing on the Hadley cell. Now the Hadley cell is a large-scale cycle in global air circulation and precipitation that's initiated near the equator and extends to 30 degrees latitude north and 30 degrees latitude in the south as well. Later in this video, we will talk a little bit about how the Hadley cell actually works. But before we do that, I want you to focus on the major takeaways of the Hadley cell. One of those is that the Hadley cell creates surface air pressures that are low at the equator and high at 30 degrees latitude north and 30 degrees latitude in the south as well.

Low surface air pressure somewhat promotes the formation of rain clouds, creating lots of precipitation at the equator. Whereas, on the other hand, high surface air pressure somewhat inhibits the formation of rain clouds, and that creates relatively low precipitation at 30 degrees latitude north and 30 degrees latitude south. Ultimately, this is going to result in a noticeable pattern of wet rainforests at the equator and dry deserts near 30 degrees latitude north and 30 degrees latitude south. In addition to the Hadley cell, there are also other similar air circulation and precipitation cells that occur between 30-60 degrees latitude, which we call the Ferrell cells, and occur between 60-90 degrees latitude, which we call the polar cells. Together, these three cells create a noticeable pattern of alternating high and low surface air pressures and alternating deserts and forests at every 30 degrees latitude.

This pattern is not perfectly maintained because there are still other variables that are at play besides just these 3 cells. However, the pattern is certainly noticeable and we'll be able to see that down below in this image and in other images as well. Let's take a look at this image down below, and what you'll notice is that we've got these latitudes labeled on the far left, which are very important to pay attention to in this image. We are also showing you the 3 cells that we talked about earlier, which again include the Hadley cell, the Ferrell cell between 30-60 degrees latitude, and the polar cell between 60-90 degrees latitude.

We are only showing you these cells in the northern hemisphere for simplicity, but it's important to remember that they also exist in the southern hemisphere as well. Again, these cells are going to create a noticeable pattern across the globe where, every 30 degrees latitude it creates alternating high and low surface air pressures and alternating deserts and forests. Starting here at the equator, notice that there is low surface air pressure at the equator, and that's going to lead to the formation of rain clouds and forests along the equator. Looking across the globe, we can see lots of green along the equator because of that precipitation, such as in Africa.

Then notice that as you go, every 30 degrees latitude, it alternates. We've got high pressure desert at 30 degrees latitude. You can see that in Africa pretty clearly. Then, low pressure forest and then high pressure desert, again, just alternating, all the way. It does the same going toward the south as well.

Over here on the right, we're going to talk a little bit more about how the Hadley cell actually works. So notice that this image here on the right is zooming into the Hadley cell in the northern hemisphere. Solar energy is going to beam down on the equator, and the equator is going to receive really high angles of sunlight throughout the year, so lots of energy and heat from the sun. That heat and energy is going to evaporate a lot of the water at the equator, and that's going to create a lot of moisture in the air along the equator. As the air gets heated up, it's going to rise up into the atmosphere.

As it rises into the atmosphere, the air will begin to cool. And when it cools, it loses its ability to retain that moisture and causes a lot of precipitation on the equator. As air continuously flows up, it's going to create pockets of low pressure at the surface just as we indicated over here at the equator, and the air that continuously goes up is going to get pushed toward the northern hemisphere. As it moves toward the northern hemisphere, the air begins to cool, and as it cools, it's going to begin to descend at 30 degrees latitude creating an area of high pressure near the surface as we indicated over here, high pressure at 30 degrees latitude. And then this air again is dry, it's lost all of its moisture.

So as it makes its way back toward the equator with low pressure, it's going to be absorbing a lot of the moisture from the land creating a desert-like environment, and essentially it's going to draw all of that moisture back toward the equator. Ultimately, this is a cycle that can continuously happen over and over again to create these patterns that we tend to see across the globe. This here concludes our lesson on broad patterns of global air circulation and precipitation, and I'll see you all in our next video.

Earth's Climate Patterns Example 3

So here we have an example problem that asks, which global air circulation and precipitation cells contribute to the dry desert terrain in Australia? And we've got these three potential answer options down below. Now taking a look at this image on the right-hand side, notice that Australia is showing up right here at this particular position, and most of Australia shows up between the 0-degree latitude or the equator and the 30 degrees south latitude. But there is a small bit of Australia that is appearing between 30 degrees and 60 degrees latitude. And so recall that the air circulation and precipitation cells that correspond with these latitudes are going to be the Hadley cell, which appears between 0 and 30 degrees latitude, and the Ferrel cell, which appears between 30 and 60 degrees latitude.

And so notice that answer option c says Hadley and Ferrel cells. And so we can indicate that option c is going to be the correct answer to this practice problem. Now option a says Hadley and polar cells, but the Hadley and polar cells are not adjacent to one another. So that is not going to be the correct answer. And then option b says Ferrel and polar cells, but the polar cell does not fall on top of Australia, and so it's not going to be affecting it, as much as the Hadley cell will.

So we can eliminate answer option b. So again, c here is correct. That concludes this example, and I'll see you on our next video.

Coriolis Effect Curves Prevailing Winds

This video, we're going to talk about the Coriolis effect and how it curves prevailing winds. Prevailing winds are winds near the Earth's surface that, over a long period of time, blow in consistent directions over a large area. To accurately detect the direction of the prevailing winds, one would need to measure the wind direction outside for several weeks, months, or years. Wind generally blows directly from areas of high air pressure down to areas of low air pressure, and it will do so in a straight line over short distances. However, over really long distances, the Coriolis effect comes into play.

The Coriolis effect is this phenomenon caused by the Earth's rotation that curves or deflects the paths of moving objects traveling really far distances, including curving and deflecting the prevailing winds. Prevailing winds moving towards the nearest pole, either the north or south pole, will be curved or deflected eastward, or in other words, they'll be curved or deflected from the west towards the east. Prevailing winds moving towards the equator will be curved or deflected westward, or in other words, they'll be curved or deflected from the east towards the west. One way that helps me remember this is that the word "equator" phonetically sounds like it has a 'w' in it, and so if winds move towards the equator, they'll be curved westward. Let's take a look at our image down below where we can start to piece some of these things together.

Notice right here in the center, we're labeling latitudes of high and low pressures, where 'HP' means high pressure and 'LP' means low pressure. All of these arrows throughout the globe represent the direction of the prevailing winds in those regions. Notice that all of these arrows are curved or deflected because of the Coriolis effect. We will interactively fill in the direction of the prevailing winds in these regions here. Notice that at 30 degrees latitude, we have high pressure, and at 0 degrees, or the equator, we have low pressure. Winds blow from high pressure to low pressure, but the Coriolis effect will curve these winds. These winds here blow toward the equator, so they'll be curved westward. Simple as that.

In the next region, 30 degrees has high pressure, 60 degrees has low pressure. Winds blow from high pressure to low pressure but again, the Coriolis Effect will curve them. These winds are not blowing towards the equator, so they won't be curved westward, they'll be curved eastward.

On the left-hand side, we have the names of the prevailing winds in each of these regions, which may or may not be necessary to know depending on your studies. These winds are named based on their region but also the direction that the winds are blowing from. For example, polar easterlies are called polar because they're in the polar region, and they're called easterlies because the winds are blowing from the east. This logic applies to all of these different names. In the northern hemisphere, the prevailing winds promote a clockwise flow, while in the southern hemisphere, they promote a counterclockwise flow. This will impact ocean currents, which we will discuss more in another video.

The last note is about the Coriolis effect causing hurricanes to rotate differently in the northern hemisphere versus the southern hemisphere. In the northern hemisphere, hurricanes rotate counterclockwise, and in the southern hemisphere, they rotate clockwise. The rotation of hurricanes in our image reflects this, with one rotating counterclockwise and the other clockwise. This counterintuitive direction results from the nature of how hurricanes form, centering around low pressure at the eye of the storm where the Coriolis effect curves the winds. With winds blowing towards the poles being curved eastward and those going towards the equator being curved westward, we see a counterclockwise flow in the depicted hurricane.

Earth's Climate Patterns Example 4

So here we have an example problem that says, if Earth rotated exactly as it does, but in the opposite direction, which of the following would likely occur? And we've got these four potential answer options down below. Now, of course, recall from our previous lesson videos that Earth rotates or spins on its tilted axis towards the east. The rotation of Earth is ultimately what determines day and night, and the speed of the rotation of Earth is what determines the length of the day. It takes about 24 hours for Earth to make one complete rotation, which is why we call a day 24 hours.

Now, if Earth rotated exactly as it does, but only in the opposite direction, then we could assume that the speed of the rotation would be the same, and then the length of the day would not be affected. That means we can eliminate answer options c and d, which both indicate that the length of the day would be affected. Option c says the days would become shorter, and option d says the days would become longer. But, again, if the rotation speed is not changed, then the length of the day would be unchanged. So now, we are between either option a or option b, which both indicate the direction of the prevailing winds at the equator.

Option a says that they would blow from west to east, meaning it would be a westerly since it's blowing from the west. Then, option b says that it would blow from east to west, meaning it would be an easterly since it's blowing from the east. Now, recall from our previous lesson videos that the Coriolis effect is going to curve or deflect the paths of prevailing winds. And recall that the winds blowing towards the equator will be curved or deflected westward. What helps us remember that is that the equator phonetically sounds like it has a 'w' in it, so we know that it's going to be deflected westward.

And so notice that westward means from the east toward the west, and so that's going to be option b. Under normal circumstances, when Earth is rotating in its normal direction towards the east, option b indicates how we would expect the prevailing winds to be deflected. But in this scenario, we know that the rotation is going to be opposite, so it's not going to be the normal situation but instead the opposite effect, which means that option a is going to be the correct answer for this problem. The prevailing winds at the equator would blow from west to east, meaning it would be a westerly, and that means the prevailing winds would blow eastward. Again, this is a hypothetical situation.

In reality, the winds blow westward at the equator. But a very interesting example problem, a is the correct answer, and I'll see you all in our next video.

Which method would be the most accurate way to find out the direction of prevailing winds?

• A. Randomly going outside one day to measure wind direction for a few hours.
• B. Measuring wind direction every day for one summer.
• C. Measuring wind direction every day for a few years.
• D. None of the above.

How Water Affects Climate

This video, we're going to talk about how water affects climate. So it turns out that Earth's global air circulation, which includes the prevailing winds that we talked about in our previous lesson videos, and ocean currents known as gyres are actually really closely interconnected with each other. And so these gyres can be defined as a massive system of circulating ocean currents, and they're so massive that they actually span entire oceans. And all of these gyres are going to be transferring heat from the equator towards the poles, which is going to have a major impact on climate globally because this process will help to distribute much of the heat and energy that's beamed onto the equator and spread that heat and energy out towards the rest of the globe, balancing the temperatures of the earth to ensure that temperatures at the equator don't get too hot and that temperatures in other parts of the globe don't get too cold. Now the reason that global air circulation and ocean currents like gyres are so closely interconnected is because the global air circulation will actually physically impact the ocean surface currents.

And this is why the directions of the prevailing winds match the direction of these ocean gyres. So recall from previous lesson videos that in the northern hemisphere, the prevailing winds promote a clockwise flow, and so all of the gyres in the northern hemisphere will have a clockwise flow to them. And in the southern hemisphere, the prevailing winds somewhat promote a counterclockwise flow, and therefore, all of the gyres in the southern hemisphere have a counterclockwise flow. So now we have what we need to complete the North Pacific and South Pacific gyres interactively. So hotter water from the equator will be transferred towards the poles and cooler water from the poles will be returned back towards the equator.

And in the South Pacific Gyre, again, hotter water from the equator will be moved towards the poles and cooler water from the poles will be returned back towards the equator to complete the circular system. Now we're going to shift gears a little bit and talk about how large bodies of water tend to stabilize the climates of nearby land. And the reason that this is possible is because water has a high specific heat, which allows it to resist temperature changes. And so while the land is heating and cooling very quickly, the water that's nearby is going to heat and cool very slowly, allowing it the opportunity to stabilize the climate of nearby land. So let's take a look at these two images on the right-hand side that kind of make this a little bit more clear.

So, in the top half, we're looking at the day, and during the day the land is going to heat up pretty quickly and the air above the land will also heat up and that hot air will rise. And the water, because it has a high specific heat, will not heat up as quickly as the land will, so it's going to remain somewhat cooler, and the air above the water will be cooler as well, so it can come in to replace that hotter air to somewhat cool down the land, during the day, and that's going to help stabilize the temperature. Now at night, we'll see something similar, but what you'll notice is the land will get cooler and the water will be warmer, and so warmer air above the water can come in to kind of heat up the land at night, stabilizing the land. So this is why you may have realized from your own personal experiences that coastal regions tend to have more stable temperatures, whereas more inland regions tend to have more extreme variations in temperature. Now last but not least, we're going to talk about how water actually absorbs and sequesters or removes carbon dioxide or CO₂, which is a greenhouse gas that traps heat in Earth's atmosphere.

And so by absorbing and removing CO₂, it somewhat helps to cool down the earth because there's less CO₂ available to trap heat in the earth's atmosphere. However, when the water does absorb CO₂, it reacts to form carbonic acid, which can change the pH of the water, and that can disrupt aquatic life. And so we can't really rely on the oceans to absorb and sequester all of the CO₂ that humans are emitting. Now this year concludes our lesson on how water affects climate, and I'll see you in our next video.

Land’s End in the southwest of England & Newfoundland in eastern Canada are both at similar latitudes, yet Newfoundland experiences significantly colder winters. Which of the following is likely the most accurate explanation for this phenomenon?

• A. Newfoundland is cloudier and therefore doesn’t receive as much solar radiation.
• B. Newfoundland is more humid, and this moisture in the air makes it feel much colder.
• C. Warm ocean currents flow towards the UK, causing a relatively warm maritime climate.
• D. All of the above.

How Mountain Ranges Affect Climate

This video, we're going to talk about how mountain ranges affect climate. So mountains can affect local climates by creating a barrier to airflow, essentially forcing the air to rise upwards into the atmosphere before it can proceed forwards. Now prevailing winds bringing moist air to mountains from one particular direction can create what's known as a rain shadow. And a rain shadow can be defined as a dry desert-like area on the leeward side of a mountain range. And the leeward side of a mountain range is really just the side that's opposite of the windward side, and the windward side as its name implies is the side of the mountain range that receives the prevailing winds.

And so in this image, notice that we've got this mountain range right here in the middle, and the arrows represent the direction of the prevailing winds. The red arrows represent warm air and the blue arrows represent cold air. And so in this image, we've got cold moist air approaching the land in this direction, and as it makes its way over the land, it heats up, which is why it turns red. Now as the prevailing winds make their way towards the mountain ranges, it's going to act as a barrier to the airflow and force the air to rise upwards into the atmosphere. And this rising air is going to cool down, which is why it turns blue again.

And the cooling air loses its ability to retain moisture, which is why it causes precipitation on the windward side of the mountain range, and that's why there's lots of vegetation on the windward side. Now as the prevailing winds make their way over the mountain, it's lost all of its moisture. And so now it's dry air, and as it descends downward, it will heat up, and that dry air will be able to absorb moisture from the land to create a dry desert-like environment on the leeward side, which is what we call the rain shadow. Now a classic example of a rain shadow is the one that's caused by the Sierra Nevada Mountains in California. So notice that on the windward side, we've got lots and lots of vegetation on this side, but then on the leeward side, we get this really large dry desert-like environment that we call the rain shadow.

So that concludes this video and I'll see you all in the next one.

Environment & Life are Interconnected

This video, we're going to talk about how the environment and life are very closely interconnected, and this is because there's actually a dynamic interplay between the environment or the climate and living organisms. And so recall from way back in our previous lesson videos that the environment is constantly changing, and living species have this incredible ability to adapt to these new environmental conditions. But what you may not have realized yet is that in turn, these relatively new evolutionary adaptations can go on to influence environmental changes, including influencing the climate. And so a classic example of how life can impact the climate are forests because they can create a cooling effect in the climate via several different methods. Now we're only going to talk about 2 processes that occur in forests that create this cooling effect, and those two processes are photosynthesis and transpiration.

Now, of course, recall that photosynthesis is the process that converts solar energy into chemical energy, which in and of itself creates a cooling effect. But also, photosynthesis removes carbon dioxide gas from the atmosphere, and carbon dioxide is a greenhouse gas that traps heat in Earth's atmosphere. So by removing carbon dioxide gas, we're also removing the heat from Earth's atmosphere, creating a cooling effect. Now the process of transpiration is somewhat analogous to sweating, and so it's actually the evaporation and release of water as a gas from the leaves of these trees and plants. Now this water that's released can go on to form rain clouds.

Those clouds can block solar radiation creating a cooling effect, and the precipitation from those rain clouds can also create a cooling effect as well. So let's take a quick look at our image down below. Notice on the left-hand side we've got a forested region and on the right-hand side, we have a deforested region. And what you'll notice is that in the forested region, much of the solar energy that's coming in is being converted into chemical energy, and so there's not as much solar radiation available to be reflected and heat up the environment. So that creates a cooling effect.

Whereas notice with the deforested region, there's a lot more of that solar energy being reflected, so that's going to create a lot of heat. And also notice in the forested region, there's a lot more cloud coverage. And over here in the deforested region, there's not much cloud coverage at all, really none. And so what we're saying is forested regions create more of a cooling effect, and deforested regions create less of a cooling effect. So that concludes this video.

I'll see you all in our next one.

Earth's Climate Patterns Example 5

So here we have an example problem that wants us to analyze the diagram and fill in the blanks, and then it says to consider an example of the complete cycle. So notice down below we've got this diagram showing a cycle, and at the very top here in green, what we have are environmental changes. Now recall from our previous lesson videos that the environment around us is constantly changing. And as the environment changes, it also alters the selective pressures on any particular population of a species. And so, of course, altering the selective pressures is going to drive evolutionary adaptations.

Now these evolutionary adaptations can go on to alter the dynamics of ecological interaction or the interactions that life has with its environment, and that can go on to drive or influence environmental changes, including influencing changes in the climate. And so now let's consider an example of the complete cycle. And so early on in Earth's history, one billion years ago, Earth's early atmosphere had lots of carbon dioxide gas and very little oxygen gas. And so this altered the selective pressures on life because most of the life was anaerobic, meaning that it did not utilize oxygen gas simply because there was not that much of it around. However, there was just enough oxygen gas for the process of photosynthesis to evolve.

And so photosynthesis alters the dynamics of ecological interactions because it changes the way that life can interact with the environment. And so now with the process of photosynthesis, life can now consume a lot of that carbon dioxide gas in the atmosphere and start to produce more of that limited oxygen gas in the atmosphere. And so over long periods of time, eventually, this is going to cause environmental changes because eventually the amount of oxygen in the atmosphere will surpass the amount of carbon dioxide in the atmosphere. And having more oxygen in the atmosphere can lead to the formation of the ozone layer, which can help to block solar radiation, again, changing the selective pressures on a population, and that can allow for evolutionary adaptations for aquatic life to now transition onto the land, now that it's safe to go onto the land with the ozone layer blocking some of the solar radiation. And now that life is on land, again, that can change ecological interactions and drive more environmental changes and so on.

And so the main point here is that environmental changes drive evolutionary adaptations, but evolutionary adaptations can go on to drive more environmental changes. So there is this dynamic interplay between the two. And so this here concludes this example problem, and I'll see you all in our next video.

Earth’s largest rain shadow occurs in south Asia, where northward-directed winds encounter the Himalayan mountains. Which of the following statements about this rain shadow is correct?

• A. Areas to the north and the south of the Himalayas have a drastically different climate.
• B. The area north of the Himalayas does not get a lot of rainfall & is a desert.
• C. As air moves northward over the Himalayas, moisture condenses & precipitates on the windward side.
• D. All of the above.

Deforestation contributes to climate change because fewer trees mean that _________ CO₂ is removed from the atmosphere, and less _______________ is absorbed, causing a hotter environment.

• A. Less; H₂O.
• B. Less; solar radiation.
• C. More; solar radiation.
• D. More; greenhouse gas.