Temperature Inside Earth: Variation & Impact | UPSC Notes

The Temperature Inside Earth is a fascinating aspect that reveals the dynamic nature of our planet. From the outer Crust to the innermost Core, temperature varies significantly, influencing geological processes. These layers contribute to the Earth’s thermal structure, playing a key role in plate tectonics, volcanic activity, and the creation of magnetic fields. Understanding the Temperature Inside the Earth involves exploring various layers:

• The Crust is the Earth’s outermost layer.
• Below the Crust lies the Mantle, a thick layer of rock.
• The Core is divided into the outer and inner Core, with extreme temperatures.

The Earth’s Crust

The Earth’s crust, the outermost layer of our planet, experiences a wide range of temperatures that vary significantly depending on depth, location, and geological conditions. Understanding the temperature dynamics within the crust is essential for studying geothermal energy, volcanic activity, and the formation of various geological features.

Surface Temperature of the Earth’s Crust

At the surface, the temperature of the Earth’s crust is primarily influenced by external factors such as solar radiation, climate, and geographical location. Surface temperatures can vary widely, ranging from below-freezing in polar regions to extremely high temperatures in desert areas. Seasonal changes also play a role in fluctuating surface temperatures.

Subsurface Temperature Gradient

As one moves deeper into the Earth’s crust, the temperature increases due to the geothermal gradient. This gradient refers to the rate at which temperature rises with increasing depth. On average, the temperature increases by approximately 25-30 degrees Celsius per kilometer of depth, although this can vary depending on local geological conditions.

Factors Influencing Temperature in the Earth’s Crust

Several factors contribute to the temperature variations within the Earth’s crust:

• Tectonic Activity: Regions with active tectonic processes, such as fault lines and plate boundaries, often have higher temperatures due to the heat generated by friction and mantle upwelling.
• Heat Flow from the Mantle: The crust is constantly heated from below by the mantle, which transfers heat through conduction and convection. This heat flow varies across different regions, influencing the temperature at various depths.
• Radioactive Decay: The decay of radioactive elements within the crust generates heat, contributing to the overall temperature profile. This process is particularly significant in regions with high concentrations of radioactive minerals.

The Mantle: Heat Engine of the Earth

The temperature within the Earth’s mantle varies significantly from the top to the bottom. Understanding these temperature gradients is crucial for studying mantle convection, volcanic eruptions, and the movement of tectonic plates.

Temperature at the Upper Mantle

In the upper mantle, temperatures range from about 500 to 900 degrees Celsius near the crust-mantle boundary. This region includes the lithosphere and the asthenosphere. The asthenosphere, which lies just below the lithosphere, is partially molten and can flow, allowing the tectonic plates to move over it.

Temperature in the Transition Zone

The transition zone, located between 410 to 660 kilometers in depth, experiences temperatures ranging from 1,400 to 1,600 degrees Celsius. This area marks a significant change in mineral structures due to increasing pressure and temperature.

Temperature at the Lower Mantle

The temperature in the lower mantle increases significantly with depth, ranging from about 1,600 to over 2,500 degrees Celsius. The immense pressure at these depths keeps the mantle solid, despite the high temperatures.

The Core: Earth’s Furnace

The temperature in the Earth’s core is incredibly high, making it one of the most extreme environments on our planet. These temperatures are central to understanding the physical properties and behaviors of the core.

Temperature of the Outer Core

The outer core’s temperature ranges from approximately 4,000 to 6,000 degrees Celsius. Despite these high temperatures, the outer core remains liquid due to the lower pressure compared to the inner core. The flow of this molten metal is responsible for creating Earth’s magnetic field through the process of convection.

Temperature of the Inner Core

The inner core’s temperature is even more extreme, estimated to be between 5,000 and 7,000 degrees Celsius. However, the immense pressure at this depth causes the iron and nickel to solidify despite the high temperatures. The combination of high temperature and pressure in the inner core leads to unique physical conditions that influence Earth’s geodynamics.

Factors Influencing Core Temperature

• Radioactive Decay: Heat generated by the radioactive decay of elements like uranium, thorium, and potassium in the core.
• Gravitational Compression: Intense gravitational forces exert pressure on the core, leading to compressional heating.
• Residual Heat from Earth’s Formation: The core retains heat from the planet’s formation, contributing to its high temperature.
• Heat Transfer from Mantle: Heat is transferred from the hotter mantle to the core, influencing the core’s overall temperature.
• Tidal Heating: Gravitational interactions with the Moon and Sun create frictional forces that generate additional heat within the core.

Temperature Variation Across Earth’s Layers

The Earth’s interior is composed of distinct layers, each with varying temperatures that influence geological processes and the behavior of materials. Understanding these temperature variations is essential for studying Earth’s structure and dynamics.

Crust

• Surface temperature varies widely based on location, ranging from below freezing to over 50°C.
• Subsurface temperature increases with depth, approximately 25-30°C per kilometer.

Upper Mantle

• Temperature ranges from 500°C to 900°C near the crust-mantle boundary.
• Increases to 1,400°C to 1,600°C in the transition zone.

Lower Mantle

• Temperatures range from 1,600°C to 3,700°C.
• Rocks exhibit plastic behavior due to intense heat and pressure.

Outer Core

• Temperatures range from 4,000°C to 6,000°C.
• High temperatures keep the outer core in a molten state, driving convection currents.

Inner Core

• Estimated temperatures are between 5,000°C and 7,000°C.
• Extreme pressure keeps the inner core solid despite the high temperature.

Impact on Earth’s Surface

• Volcanic Activity: Heat from the mantle causes magma to rise, leading to volcanic eruptions that shape landscapes and release gases into the atmosphere.
• Earthquakes: Temperature-driven movements in the mantle and crust create stress, leading to faulting and seismic activity that impacts Earth’s surface.
• Mountain Formation: Convection currents in the mantle drive plate tectonics, causing the collision and uplift of crustal plates to form mountain ranges.
• Geothermal Energy: The heat from the Earth’s interior is harnessed as geothermal energy, providing a renewable source of power in regions with high geothermal activity.
• Hydrothermal Features: Temperature variations create hot springs, geysers, and fumaroles, which are visible manifestations of geothermal energy near Earth’s surface.
• Oceanic Ridge Formation: Mantle upwelling at divergent boundaries leads to the creation of mid-ocean ridges, contributing to seafloor spreading.
• Impact on Climate: Volcanic eruptions influenced by interior heat release aerosols and gases, which can lead to temporary climate changes and cooling effects.

Conclusion

The Temperature Inside Earth is a crucial aspect of our planet’s dynamics. From the relatively cool Crust to the fiery Core, temperature variations play a vital role in shaping the Earth’s surface and maintaining life. Understanding these temperatures helps us appreciate the complex processes that drive the Earth’s geology and climate. Whether it’s the creation of new land through volcanic activity or the movement of continents, the heat from within the Earth is the engine that powers these processes.

Temperature Inside Earth UPSC Notes

1. Temperature increases with depth inside the Earth, reaching extreme levels in the core. 2. Crust temperatures vary widely based on location and depth, influencing surface conditions. 3. Mantle temperatures range from 500°C to 4,000°C, affecting magma formation and tectonic activity. 4. Core temperatures are the highest, estimated between 4,000°C and 6,000°C, sustaining Earth’s magnetic field. 5. Heat flow from the interior to the surface is critical for volcanic and geothermal activity. 6. Pressure significantly impacts temperature, with higher pressures increasing thermal conductivity. 7. Geothermal gradient measures temperature changes with depth, providing insights into Earth’s thermal structure. 8. Heat production in Earth’s interior comes from radioactive decay and residual primordial heat.

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