Earth Systems and Weather
The Earth's Atmosphere
For the past few lessons, we’ve been talking about the importance of what lies below the Earth’s surface, or, the mysterious layers of the Earth. But...what about everything above it? The parts of the Earth above the surface are known as the atmosphere. At first, it might just seem like empty space to you, but in reality, the atmosphere has so much significance for us.
So what is the Earth’s atmosphere, exactly? Well, the atmosphere is a thin layer of gas surrounding the planet, which allows life to exist on Earth. Think of it as a blanket for Earth, which absorbs and traps the right amount of heat from the sun, and keeps the planet at a liveable temperature, so we don’t all melt or freeze to death. It even acts like a shield for us, protecting us against harmful radiation.
One important aspect of the atmosphere, though, is that it has all the gases, such as oxygen and CO2, that organisms need to survive on this planet. The atmosphere is made of 78% nitrogen, 21% oxygen, and 1% other gases. such as Argon, Carbon Dioxide, Water Vapor, Ozone (which is a colorless, toxic gas), Methane, Carbon Monoxide, and Hydrogen. Some of these “other gases” are crucial for this planet as well. Water vapor is a very fine mist that creates clouds and weather, while ozone absorbs UV radiation from the sun. Finally, greenhouse gases, such as CO2, are gases that work like a greenhouse, and trap heat from the sun!
Our atmosphere also contains aerosols, which are salts evaporated from oceans, dust from the ground, pollen from plants, ash from volcanoes, acids, and other parts from human pollution. Aerosols are necessary, but only in moderation, because they reflect and absorb the sunlight, which affect weather and climate change on our planet.
The atmosphere contains many layers, all of which serve an important purpose. First, we have the troposphere, which is the layer closest to the Earth, and the layer that contains the air we breathe. It has most of the weather and air molecules, and is heated by the warmth of the Earth’s surface. This is why the higher you go into the troposphere, the colder it gets.
Next, we have the stratosphere, the layer above the troposphere where most airplanes and aircrafts fly. The ozone layer is located on top of the stratosphere, absorbing UV radiation. This means that as you go up the stratosphere, it gets warmer and warmer.
The layer just above the stratosphere and the ozone layer is the mesosphere. Here, the temperature drops drastically, with little to absorb sunlight. Ironically, even though this is a cold cold place, meteors that enter our solar system usually burn up here.
Above the mesosphere is the thermosphere, which is actually the hottest layer in the atmosphere. This is because the thermosphere is in charge of filtering out gamma-rays and X-rays from the Sun.
Finally, the thermosphere leads to the exosphere, the outermost layer of the atmosphere. The exosphere has almost no atmosphere, and eventually fades into the vast darkness of Space.
So, everytime you walk outside and DON’T get a sunburn, you’ve got the atmosphere to thank for that. You’ve also got the atmosphere to thank for protection from other kinds of radiation, but also for the air we breathe, and life in general. In the next unit, we’ll explore the role of the atmosphere in another important process: the water cycle. See you then!
The Water Cycle
What if I told you that the water in your water bottle right now could be the same water your great great grandmother showered in a century ago? Yeah, you probably don’t believe me, and you’re probably pretty grossed out too. But hey, this is actually possible, all thanks to a little thing called the water cycle.
The water cycle is how water gets through the land and atmosphere. It consists of five stages: evaporation, transpiration, condensation, precipitation, and finally runoff, repeated over and over again. Let’s go through each of these stages one by one, in order to see how we really get our water.
First, it’s evaporation, where liquid changes to vapor through heating. Remember when I said that the atmosphere contains water vapor, which is really important for our Earth? Well, here’s how it gets there, and it’s importance. The Sun’s rays heat saltwater from oceans, freshwater, and water on the ground, transforming it into water vapor. This water vapor then rises into the atmosphere. Another way that water is released into the atmosphere is through transpiration, when the leaves of plants release water vapor into the air. In short, evaporation and transpiration are the stages that get water vapor into the air.
After these two stages comes condensation, which is when a gas changes into a liquid through cooling. After water has been evaporated, the air cools down, and the water molecules clump together to form tiny droplets of liquid water. These tiny droplets then cluster together to form clouds, and these droplets slowly get bigger, and bigger, and bigger.
This is when precipitation occurs. The water droplets in these clouds get large and heavy, and fall from the atmosphere in various ways. Precipitation normally occurs in the form of rain, but during colder temperatures, it could often fall in the form of snow, hail, and sleet. However, these three will eventually melt into water as well.
This is when runoff occurs. When precipitation forms on the ground, this water accumulates. It gets absorbed and funneled into streams and rivers, which will eventually flow back into lakes, ponds, and the ocean. Water flowing above the ground is called runoff, while water flowing below the ground is called groundwater. However, both runoff and groundwater will eventually end up in larger bodies of water.
Even though this is the last stage, the cycle is far from over. When warm air passes into the ocean or any other body of water, it will again become evaporated, beginning the cycle again. Keep in mind that water will be stuck in this cycle forever. It never leaves or enters the cycle, rather, it just gets cycled through different forms.
This water cycle has been happening ever since the Earth was formed, which means that for millions of years, organisms have been using the same water. So really, the water in your water bottle right now could actually be the same water your great great grandma showered in, and it could even be the same water that a dinosaur drank during the jurassic age! In the next lesson, we will be talking about the weather, and the impact that the water cycle has on it. See you then!
Condensation in a Cup - Experiment
Precipitation in a Cup - Experiment
When the cloud gets too heavy, the drops fall through as rain! When water droplets condense to the point where they become too heavy, gravity pulls them down from the clouds as rain. What stage of the water cycle is this? (Precipitation)
Weather, Part 1
Have you ever walked outside, enjoying warm temperatures and breezy weather, and then heard a thunderclap and felt the first raindrop five minutes later? Have you ever been so excited in the winter because the forecast predicted snow showers...which just...never came? That can get pretty annoying, but hey, that’s the weather for you. But what exactly is weather?
Weather is the condition in the atmosphere at a given place and time, and there are several factors that influence it. These factors include air temperature, wind, humidity (which is the amount of moisture in the air), clouds, and precipitation. Let’s explore each and every one of these factors, and how it plays a role in our weather forecast.
The first factor is air temperature. Air of different temperatures causes air pressure and density differences, where warmer temperatures correlate with higher pressures and lower densities, while colder temperatures correlate with lower pressures and higher densities.
Different air temperatures also cause water to vaporize when it’s warm, and condense as precipitation when it’s cold, which explains the evaporation and precipitation stages of the water cycle!
Humidity levels are also affected by air temperature. Warmer air holds more water, because molecules move around faster and don’t clump into water droplets as quickly. Furthermore, when cold air reaches warm air, the water in the air condenses, which is what causes precipitation. As you can see, air temperature influences a lot of the other factors, such as wind and precipitation, that impact our weather.
Let’s dive deeper into winds, which are a result of uneven heating of air in the atmosphere that causes different air temperatures. These differences are what create wind, when air of higher pressure moves to an area of air with lower pressure. They also result in convection currents, when warmer and less dense air rises, and cooler and denser air sinks.
Now, there are two types of winds that impact our weather, Global Winds and Local Winds. Global Winds are a result of different air temperatures around the world. The sun’s rays strike the Earth more directly and at a higher intensity near the equator than at the poles. Therefore, air heats up more near the equator, and warm air from the equator rises up and moves towards the poles. Meanwhile, cold air from the poles moves towards the equator. These are what cause winds to loop across the entire planet. The Earth’s rotation also causes the movement of air from the equator and poles to curve in different directions as well. Winds curve towards the east and west, creating predictable wind patterns in different parts of the world.
Meanwhile, Local Winds are our daily breezes that occur where the ocean meets the land. Land cools and warms faster than water, which cause differences in air temperature. During the day, since the land is warmer, cooler air moves from the ocean to the land, causing a sea breeze. Meanwhile, during the night, the opposite occurs, when wind moves out onto the ocean from the land. This is called a land breeze.
We have just gone over the effects of air temperature and wind on the daily forecast, but there is still quite a ways to go. In the next lesson, we’ll be looking at the impact of other factors on the weather as well. See you then!
Weather, Part 2
In the last lesson, we went over the effects of air temperature and wind on the daily forecast, but...things can get quite a bit more complicated than that.
Another factor that affects weather is humidity, or the amount of moisture and water vapor in the air. Note that humidity is always reported in “relative humidity”, which is the amount of humidity in the air compared to how much the air can hold. When air is at 100% relative humidity, this means that air molecules are completely saturated, and cannot hold any more water vapor. There is also a certain air temperature and humidity called a dew point, a point at which water droplets (or dew drops) form on grass. These droplets are formed when water condenses from the air. Dew point depends on both the amount of water vapor in the air, as well as air temperature.
Clouds are also factors that play into our weather, and are very similar to humidity as well. When water vapor in the air condenses, it forms a cloud, and when a cloud is formed, this indicates that water vapor in the air has reached its dew point. Clouds form when moist air cools and water vapor condenses onto small dust and salt particles (called aerosols, remember those?) in the atmosphere. This condensation forms tiny water droplets and ice crystals, which are what make up clouds. Different types of clouds, which signify different kinds of weather, are often identified by their shape and altitude in the atmosphere.
The final factor that affects our weather are air masses. These are large bodies of air that move across land, which bring in different types of weather. There are two major types of air masses: cold fronts and warm fronts. A cold front occurs when a cold air mass is moving in to replace a warm air mass. Meanwhile, during a warm front, a warm air mass moves in to replace a cold air mass, often producing rain. Cold fronts and warm fronts have different densities, which means that they do NOT get along very well. Instead, these air masses either rise or sink beneath the other air mass. Often, when warm and cold fronts meet, and warm air rises while cold air sinks, this causes rain, and even storms!
Now, there are two fronts that occur when a cold and warm front both move in. The first is a stationary front, when cold and warm air meet...and stay put. Once either front begins to move forward, however, it will become an occluded front, and not a stationary front any longer. In an occluded front, a cold and warm air front collide, but the cold front moves faster, pushing the warm front up. This is what produces rain.
So there we have it. All of these factors are why the weather can become so unpredictable. They’re the reason why temperatures are warm and sunny one minute, and rainy and depressing the next. However, sometimes, the weather can become a bit...scary. In the next lesson, we’ll be talking about different types of severe weather, what causes them, and just how terrifying they can get. See you then!
Severe storms really suck. You have to stay home all day, wondering how much your house is going to get destroyed...and it’s even worse when the power goes out. But how do these types of storms even occur, and why do they exist? We’ll look into each type of storm and find out.
First, we’ve got the most basic example, thunderstorms. During thunderstorms, warm, moist air moves quickly up into the atmosphere, and cools electric charges that form on air molecules. This creates a negative charge at the bottom of a storm cloud, and a positive charge on top, and the cloud will also induce a positive charge on the ground. These positive and negative charges rush towards each other, creating a bolt of lightning. Now, this lightning is VERY hot, and even explodes the nearby air. This air expands faster than even the speed of sound, producing thunder. As discussed earlier, precipitation then falls from the cloud to the ground, completing the dangerous thunderstorm.
Okay, but thunderstorms are probably the least damaging compared to other severe weather phenomena, and compared to tornadoes, they definitely seem like a nice breeze. During a tornado, warm air rises quickly, and this updraft creates a funnel cloud. If the funnel cloud reaches the ground, it creates a temporary swirling vortex, called a tornado. This swirling vortex starts small, and will either diminish into nothing...or become a massive beast. Tornadoes are quite destructive, but they usually last a short time, and stay in a small area. Emphasis on the word usually.
But c’mon, tornadoes are far from the worst it can get, because nature still has its last and greatest trick up its sleeve: Hurricanes. Hurricanes are the most powerful type of storm, and are formed in low-pressure areas over tropical waters. These low pressure areas of warm, moist air rise, and cause powerful winds. The rotation of the Earth then causes the winds and clouds to swirl in a counterclockwise direction in the northern hemisphere, and in the middle of the swirling action, there will be a small area in the center, known as the eye of the hurricane. Surprisingly, the eye of the storm is an area of calm, while the rest of the storm brings chaos and destruction. When hurricanes come on land, the winds are enough to blow away entire houses, and the rains are enough to flood cities. Yeah, no other storm could ever dream of being this evil.
Yeah, severe storms, especially hurricanes, are absolute nightmares. But thankfully, they get over pretty soon...at least most of the time...and you can usually go back to having a normal life after the storm passes. In the next lesson, we are going to talk about climate, what affects climate, and how it is different from weather. See you then!
Warm Air Rises, Cold Air Sinks - Experiment
Tornado in a Jar - Experiment
There are all different kinds of places on Earth. Some are tropical, with really hot temperatures and a variety of animal and plant life, some have ice and snow, and some are right in the middle. All of these places have different climates, which is what makes them all unique.
Now, climate is very different from weather. While weather includes the daily forecast and conditions during a specific time, climate is defined as the average weather conditions of an area, over a long period of time. Like weather, climate includes information about temperature and precipitation, but this information is collected over a long period of time. Now, we’re going to talk about some of the factors that influence climate, and make every location unique.
The first factor is latitude, the distance of a location from the equator, be it north or south. Different latitudes get different amounts of light and heat from the sun. The sun’s rays hit areas near the equator more directly, so these areas are generally warmer. On the other hand, areas near the poles, which get sunlight at low angles, are pretty cold!
Scientists have separated the Earth into climate zones, based on latitude. First is the tropics, which extends from 23.5 degrees north to 23.5 degrees south, and includes the equator! These areas have some of the hottest temperatures on Earth, and are usually quite tropical. The next zone is the temperate zone, which goes from 23.5 degrees to 66.5 degrees North, and 23.5 to 66.5 degrees South. These areas have moderate temperatures, but they can get cool or warm depending on the season. Finally, there are the polar zones, which are north and south of the 66.5 degree lines. Polar zones get little solar radiation, so these places are freezing all year.
The next factor that affects the climate of an area is its elevation, or height above sea level. As we learned earlier, the higher up in the atmosphere you go, the fewer molecules of air there are, which means fewer molecules that absorb heat from the Earth’s surface. Therefore, temperatures are colder higher up, and this is the opposite for places with lower elevations.
Water also has a huge impact on the climate of an area. Since water takes longer than air to heat up and cool down, coastal areas have less of a fluctuation in temperatures. This means that the seasons of winter and summer are not as extreme, because it can’t get that much warmer or cooler. On a global scale, ocean currents also affect coastal climates. Warm water from the equator forms currents that move outward, which warm nearby air and land. This warm water then travels up to the poles, and cooled water returns to the equator, cooling the air and land it passes.
Mountains also have a great impact on the climate of an area. They do provide high elevations that affect temperature, but mountains impact rain patterns as well. Warm air first bumps into mountains. It then rises and cools down because of these high elevations. As it cools, it follows the next steps in the water cycle. It condenses in the air and precipitates to form rain. But, after the air has dumped all of its moisture onto the mountain, the air is left dry. This forms a rain shadow, a place where little precipitation falls.
Now, you’ve learned about climate and how different factors affect the climate of a certain place, it is time to look at how the climate can be changed, through natural ways as well as through some of the destructive habits that humans have. See you then!
As we know, the climate of an area would be the weather conditions that occur in the area over a general period of time. However, that doesn’t mean the climate can’t be changed.
There are loads of changes that occur naturally that can alter the climate of many regions. First, there are atmospheric particles. As solid and liquid particles get back into the atmosphere, they increase the amount of cloud cover, which blocks the sun’s radiation from warming the Earth. Climate is also changed by solar radiation changes as well. The sun doesn’t always radiate the same amount of energy, and sometimes even gets sunspots, which are darker, cooler spots on the sun. Finally, the Earth’s movements can change a local climate as well, because it will change the angle at which the sun strikes the Earth, causing temperatures to change too.
However, there is one looming threat to our climate, and that is, you’ve guessed it: us. Humans.
Our cities affect the local climate a lot. Since there are lots of buildings and black asphalt, they absorb heat from the sun, which therefore heats the air. Meanwhile, rural areas have lots of vegetation that cools the air, which explains why they might be cooler than the big cities.
However, our cities and urbanization is starting to become very problematic. As our towns slowly turn to densely packed cities, with loads of black asphalt, more and more regions of the world are getting warmer. And that’s not the only way us humans have impacted the climate.
Our activities have also increased the amount of greenhouse gases in the atmosphere. Now, greenhouse gases are gases that trap heat in the atmosphere, such as carbon dioxide and sulfur dioxide, and the greenhouse effect is the warming of the atmosphere by these gases that trap heat. Greenhouse gases are essential because the heat they trap allows plants and animals to survive. However, human activities have caused levels of greenhouse gases in our atmosphere to skyrocket.
Since the late 18th century, people have mined and burned enough fossil fuels, for transportation and electricity, to increase carbon dioxide levels way beyond historically normal range. And...this carbon isn’t being absorbed fast enough to balance the amount that humans have added. Because of this, scientists determined that greenhouse gas emissions are what are really causing global warming, and are changing our climate.
And we can see the destructive effects of our actions in various ways. Ice caps in polar regions are starting to melt. More and more forest fires, including the infamous Australian Bushfires, are occurring. Sea levels are rising. Habitats are changing, so much so that it isn’t safe for animals to survive in what was once their home. And finally, there are extreme weather events and patterns, such as increased hurricanes, that are coming to bite us back.
We have to stop this climate change, and protect our planet from the damage that we have already done. In the next unit, we will learn more about organisms and ecosystems in all climate types, and we will touch on how our actions can affect their lives as well. See you then!