Earth Science Module PDF

MODULE 1: EARTH SYSTEMS Lesson Objectives: a. Describe the Earth’s four spheres. b. Explain how the Earth can be viewed as a system and a group of systems. c. Draw an illustration how the four spheres are interconnected with each other. d. Explain the effect o...

MODULE 1: EARTH SYSTEMS Lesson Objectives: a. Describe the Earth’s four spheres. b. Explain how the Earth can be viewed as a system and a group of systems. c. Draw an illustration how the four spheres are interconnected with each other. d. Explain the effect of humankind on the Earth’s systems. Pre-Competency Checklist Using the illustration below, list down the matters that can be found on earth that belong to each sphere of the planet. A habitable planet is one that can sustain life for a significant period of time. It has water, energy, and nutrients that are needed by all organisms. Most importantly, a habitable planet must receive enough heat to maintain liquid water on its surfaces. Those characteristics of a habitable planet make the Earth a special planet. It is in the habitable zone, a region where planets can receive enough heat to retain liquid water on their surfaces. It has a magnetic field that keeps the planet from harmful solar radiation, it has an insulating atmosphere, and it contains the essential chemical components for life. Those essential elements, including carbon, are continuously cycling through the earth due to several processes. Life on earth is maintained by this cycle, which leads to the formation of mineral and energy resources that serve as the basis of contemporary technological civilization. In this module, you will learn about what makes the Earth a system and how those systems are interconnected with each other. Let’s Study! The Earth’s Four Spheres a. The geosphere, sometimes called the lithosphere, is the portion of the earth that includes rocks and minerals. It contains the cold and hard solid land of the planet’s crust, the semi-solid land underneath the crust, and the liquid land near the center of the planet. Layers of the Earth ▪ Crust is the outermost shell of the planet Earth. It is generally divided into two types: continental crust, which is older and thicker, and oceanic crust, which is younger and denser. This layer is Figure 1.1 Layers of the Earth extremely thin, cold, and brittle compared to Source: https://www.snexplores.org/article/explainer-earth-layer- layer what lies below it. This is made up of about 98% of elements such as oxygen, silicon, aluminum,  iron, calcium, sodium, potassium, and magnesium, and the rest is composed of elements like nickel, sulfur, manganese, hydrogen, titanium, phosphorus, carbon, and others. Under the oceans (and Hawaiian Islands), it may be as little as 5 kilometers (3.1 miles) thick. Beneath the continents, the crust may be 30 to 70 kilometers (18.6 to 43.5 miles) thick. ▪ The mantle is the Earth’s thickest layer which is about 2,900 kilometers thick. This layer is mostly made up of iron, magnesium, and silicon, it is dense, hot, and semi-solid. The temperature of the mantle varies greatly, from 1000°C (1832°F) near its boundary with the crust, to 3700°C (6692°F) near its boundary with the core. In the mantle, heat and pressure generally increase with depth. The upper mantle is mostly but its more malleable regions contribute to tectonic activity. Two parts of the upper mantle are often recognized as the lithosphere and asthenosphere. The lithosphere is the rock outer part of the Earth which is made up of brittle crust and the top of the upper mantle. it is the most rigid and coolest part of Earth. The division in the lithosphere between the crust and the mantle is called the Mohorovicic discontinuity. The asthenosphere is the denser, weaker layer beneath the lithospheric mantle. The temperature and pressure of the asthenosphere are so high that rocks soften and partly melt, becoming semi-molten. The asthenosphere is much more ductile and viscous than either the lithosphere or lower mantle. The very slow motion of lithospheric plates “floating” on the asthenosphere is the cause of plate tectonics, a process associated with continental drift, earthquakes, the formation of mountains, and volcanoes. The lower mantle is hotter and denser than the upper mantle. The lower mantle is much less ductile than the upper mantle. Although heat tends to soften the rocks, intense pressure keeps the lower mantle solid. Convection currents occur in the mantle and are the result of differential heating. It transfers hot, buoyant magma to the lithosphere at plate boundaries and hot spots. Convection currents also transfer denser, cooler material from the crust to Earth’s interior through the process of subduction. As a result, it drives the movement of the Earth’s rigid tectonic plates in the fluid molten mantle. ▪ The earth’s core is very hot and very dense center of the planet. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). The primary contributors to heat in the core are the decay of radioactive elements, leftover heat from planetary formation, and heat released as the liquid outer core solidifies near its boundary with the inner core. The outer core is made from iron and nickel, just in liquid form. Heated largely by the radioactive decay of the elements uranium and thorium, this liquid churns in huge, turbulent currents. That motion generates electrical currents. They, in turn, generate Earth’s magnetic field. The inner core is extremely dense, it’s made mostly of iron and nickel in solid form because of extremely high pressure at the center of the earth. The pressure and density are simply too great for the iron atoms to move into a liquid state. b. The hydrosphere contains all the solid, liquid, and gaseous water of the planet. It includes the oceans, rivers, lakes, groundwater, and water frozen in glaciers. The 97% of water on earth comprises the ocean; the remaining 3% is found in glaciers and ice below the ground, in rivers and lakes, and 1.2% out of the 3% can be used as drinking water. c. The atmosphere includes all the gases surrounding the Earth. All planet has an atmosphere, but Earth is the only planet with suited combination of gases to support to life. Even though these gases consist of particles that are too small to be seen, they still have weight that pushes down on earth, creating what is called air pressure – the weight of air above us. Layers of the Atmosphere Troposphere makes up approximately 75% of the total mass of the atmosphere, contains 99% of the atmosphere’s water, and is the layer where atmospheric Figure 1.2 Layers of the Atmosphere Source: https://www.ces.fau.edu/nasa/module- gases are most concentrated. It extends upward to about 2/atmosphere/earth.php  10 km above sea level. Nearly all weather phenomena, turbulence, and clouds occur in this layer. Air temperature in the troposphere typically decreases as altitude increases as a result of three mechanisms of heat transfer; the radiation, conduction, and convection. The troposphere is generally warmest near Earth’s surface and coolest at its highest point. Stratosphere extends from the top of the troposphere to about 50 km above the ground. The infamous ozone layer is found within the stratosphere. Ozone molecules in this layer absorb high-energy ultraviolet (UV) light from the Sun, converting the UV energy into heat. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone. Temperatures in the stratosphere are highest over the summer pole, and lowest over the winter pole. Mesosphere which lies above the stratosphere and stretches to approximately 90 km above the Earth’s surface. Most meteors burn up in the mesosphere. In the mesosphere, temperature begins to decrease again. The mesosphere’s lower temperature results, in part, from the low concentration of ozone, so little solar radiation is absorbed in this layer. The air in this layer is too thin and the air pressure is very low. Thermosphere is the layer that extends approximately 600 km beyond the Earth’s surface and where most of the high-energy X-rays and UV radiation from the sun are absorbed, raising its temperature to hundreds or, at times, thousands of degrees. However, the air in this layer is so thin that we could feel extremely cold. This layer is composed mainly of nitrogen and oxygen molecules. Many satellites actually orbit Earth within the thermosphere. The region of the atmosphere that extends from 60-300 km above the Earth’s surface is called ionosphere, which is located within the thermosphere. It contains a large number of electrically charged atoms and molecules due to the constant collision of gas molecules and atoms with high-energy X-rays and ultraviolet light from the sun. These collisions resulted in knocking the electrons off of the atoms and molecules, creating electrically charged ions and free electrons. Auroras occur within the thermosphere. Solar particles trapped here interact with different types of gas molecules, mostly nitrogen and oxygen, resulting in unique, colored displays of light. Oxygen gives off green and red light, while nitrogen glows blue and reddish-purple. Exosphere is the region above the thermosphere that extends to 10, 000 km above the Earth’s surface. In this layer, atoms and molecules escape into space, and higher altitude satellites orbit our planet. The air in the exosphere is very, very, very thin, making this layer even more space-like than the thermosphere. It contains mainly hydrogen and helium and several heavier molecules such as oxygen, nitrogen, and carbon dioxide atoms, but there are so few of them that they rarely collide, and some of them escape right out into space. The temperature of the exosphere can reach up to 2,700 °F (1,500 °C) during intense solar storms. Moreover, temperature increases into the thousands of degrees Fahrenheit during the day when molecules absorb solar radiation, and drops well below freezing at night. d. The biosphere contains all the planet’s living things. This sphere includes all the microorganisms, plants, animals, and people of Earth. This portion of the Earth interacts with all other spheres. Living things need water (hydrosphere), substances from the atmosphere, and nutrients gained starting from the soil to eating things in the biosphere. Earth is a dynamic planet and can be viewed as a system; life, the atmosphere, the oceans, and the land are constantly changing and interacting in different ways. Earth can also be viewed as a closed system because only energy is naturally entering and being transferred outside the atmosphere. The water cycle, carbon cycle, and nutrients cycle replenish and maintain what life needs and help regulate the climate system. Though these different systems, which are complex processes, have individual functions, they are still linked to each other and comprise the Earth system. With one change in one of those complex processes or cycles, other systems will also be affected. Explore 1. How do humans affect the Earth system? 2. Draw an illustration of a situation, geological processes or natural phenomena that shows the interconnection of the four spheres of the Earth.