Heat Budget of Earth: Heat is a form of energy, received by the earth from the sun. Heat Budget deals with the amount of heat energy received from the sun and its utilization in the atmosphere and the surface of the earth. This explains why the earth neither warms up nor cools down despite the huge transfer of heat that takes place.
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Heat Budget of Earth Diagram
Heat Budget of Earth
What is Heat Budget of Earth?
The Earth’s heat budget refers to the balance between incoming and outgoing energy, similar to a financial budget but dealing with energy instead of money. It’s a crucial aspect of understanding our planet’s climate and its potential changes.
Here’s a breakdown of the key points:
Incoming Energy
- Shortwave radiation: This is the main source, coming directly from the Sun as high-energy, short-wavelength radiation.
- Longwave radiation: This originates from other sources like Earth’s internal heat and the atmosphere, with lower energy and longer wavelengths.
Outgoing Energy
- Reflected shortwave radiation: About 30% of incoming sunlight bounces back to space, mainly from clouds and ice.
- Longwave radiation emitted by Earth: This is the primary heat loss, primarily radiating back into space.
- Longwave radiation absorbed by the atmosphere: Some Earth radiation is trapped by greenhouse gases, contributing to warming.
Balance and Importance
- The heat budget is balanced when incoming and outgoing energy are equal, maintaining a stable average temperature.
- An imbalance can lead to temperature changes, potentially impacting climate. Understanding this balance is crucial for studying climate change.
- Changes in greenhouse gases or other factors can alter the balance, leading to warming or cooling trends.
Heat Budget of Earth – explained with an example
It is believed that a heat balance exists between the amount of solar radiation received by the earth’s surface and its atmosphere and the amount of heat lost by the outgoing terrestrial longwave radiation from the earth’s surface and the loss of heat from the atmosphere. The state of balance is known as the heat budget of the earth.
35 units of the heat out of the total 100 units coming from the sun has been reflected into space even before reaching the earth’s surface. Out of these 35 units, 6 are reflected and scattered by the upper atmosphere, 27 by the clouds, and 2 mainly the snow-covered surface of the earth. The reflected part of the sun’s radiation is known as the Albedo of the Earth. The remaining 65 units are absorbed by the atmosphere, 14 units of these are absorbed by the atmosphere, and the remaining 51 units by the earth’s surface.
The 51 units absorbed by the earth are again radiated back in the different forms of terrestrial radiation. 17 of these are radiated back directly into the space and the remaining 34 units are absorbed by the atmosphere in the form of convection, turbulence, and latent heat of condensation. Finally, the atmosphere also radiates back 48 units i.e. 14 from solar radiation and 34 from terrestrial radiation back into space.
Hence, the sum total of the heat going out of the earth is 65 units i.e. 17 from the earth’s surface and 48 from the atmosphere. In this way, there is a balance between the incoming 65 units and the outgoing 65 units. This delicate and dynamic balance of heat is termed as Heat Budget of the Earth.
Components of Heat Budget
The components of heat budget are as follows:
- Reflection: Reflection happens when incoming solar radiation hits a surface in the sky, on land, or on water and bounces back without producing heat.
- Absorption: Radiation absorption is the process of transforming electromagnetic radiation into heat energy.
- Scattering: When solar radiation collides with tiny things in the Earth’s atmosphere, such as air molecules, water droplets, or aerosols, the radiation scatters, spreading the solar waves in all directions.
- Terrestrial Radiation: Longwave radiation emitted by the Earth’s surface or its atmosphere is called terrestrial radiation. The processes that Terrestrial Radiation uses to keep the temperature balanced include the following:
- Latent heat transfer: Latent heat is the heat or energy absorbed or released during a substance’s phase change. It could transition from a solid to a liquid, from a liquid to a gas, or vice versa. The amount of heat transferred when one substance is prepared to change its condition is known as latent heat transfer.
- Sensible heat transfer: The energy needed to increase a substance’s temperature without inducing a phase shift is known as sensible heat. Sensible heat transfer occurs when energy is supplied to an object as heat without causing the object’s state to change. The earth or the air itself may absorb sunlight, causing a shift in temperature.
- Emission by vapour and clouds: The clouds and water vapour also emit significant amounts of terrestrial radiation.
Importance of Heat Budget of Earth
- One of the main things that keeps the Earth habitable is its thermal balance, which is achieved via the planet’s heat budget.
- It maintains Earth’s temperature.
- Improving the production of solar panels that absorb and transform this energy is imperative.
- It is responsible for the temperature differential between the equator and the poles.
- It facilitates photosynthesis, which in turn promotes plant development.
- It is also in charge of the differences in rainfall patterns between the equator and the poles.
Effects of Heat Budget of Earth
The balance between thermal radiation emitted by the Earth and solar radiation arriving from space is known as the Earth’s heat budget, and it has a significant impact on the climate system. Variations in this energy balance have the potential to impact both local and global climates. The following are the main ways that the Earth’s heat budget affects the climate system:
- Global Warming and Climate Change: As a result of human actions like deforestation and the combustion of fossil fuels, the atmosphere now contains more greenhouse gases. The enhanced greenhouse effect is a result of these gases’ increased ability to trap outgoing heat radiation. Global warming is the outcome, which causes variations in precipitation regimes, temperature patterns, and climate zones.
- Melting of Ice and Sea Level Rise: Changes in the Earth’s heat budget contribute to the warming of the planet, leading to the melting of polar ice caps and glaciers. This meltwater contributes to rising sea levels, with implications for coastal areas and low-lying islands.
- Ocean Currents and Heat Transport: The heat budget influences ocean currents, which play a crucial role in redistributing heat around the globe. Changes in these currents can impact regional climates and have cascading effects on marine ecosystems and fisheries.
- Impacts on Agriculture and Water Resources: The heat budget’s effects on climate patterns can have an impact on water supplies and agricultural productivity. Crop yields and the availability of water for use in agriculture and human consumption can be impacted by changes in precipitation patterns, temperature extremes, and modified growing seasons.
Variation in the Heat Budget of Earth
- The Earth still maintains a balance between terrestrial radiation and insolation, although this is not the case at any latitude.
- In the tropical zone, the heat budget and insolation are greater than the terrestrial radiation. It is therefore an area with an abundance of heat.
- In the arctic zone, heat gain is smaller than heat loss. It is therefore a region experiencing a heat shortage.
- This imbalance is partially mitigated by winds and ocean currents, which transfer heat from hot spots to areas with excess heat.
- The term “latitudinal heat balance” refers to this process of latitudinal heat redistribution and balancing.
How is the Heat Budget of Earth Analyzed and Calculated?
Suppose that the top of the atmosphere receives 100% of the insolation. Only a small portion of the energy that enters the atmosphere is absorbed, scattered, and reflected, returning the remaining energy to the Earth’s surface.Before the radiation even reaches the surface of the Earth, about 35 units are reflected into space. The Earth’s albedo is the total of these, of which 27 are reflected from cloud tops and 2 from regions covered in snow and ice.
51 units of terrestrial radiation are emitted by the Earth. Thirty-four of them are absorbed by the atmosphere, while seventeen are released straight into space. Six of these are absorbed immediately, nine via turbulence and convection, and nineteen through the latent heat of condensation. The Earth and its atmosphere absorb the remaining 65 units. Of this, 51 units are absorbed by the Earth’s surface, while 14 units are absorbed within the atmosphere.
The 48 units that the atmosphere emits back into space are made up of 34 units from terrestrial radiation and 14 units from insolation.Since the total radiation returning from Earth and the atmosphere is 17 and 48 units, respectively, the 65 units of solar insolation received are balanced by the total radiation returning from Earth and the atmosphere.
Conclusion
The ultimate source of heat is the sun. The primary cause of all climatic characteristics is the differential heat received from the sun, which is distributed unevenly throughout the world. Thus, knowledge of the Earth’s heat budget and seasonal temperature distribution is essential to comprehending other aspects of the climate, such as precipitation, wind, pressure, and so forth.
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Heat Budget of Earth – FAQs
What is the Earth’s energy budget?
The Earth’s energy budget is a balance between the incoming solar radiation (shortwave radiation) and the outgoing thermal radiation (longwave radiation) emitted by the Earth. It represents the flow of energy in and out of the Earth’s atmosphere.
What is the primary source of energy for the Earth’s heat budget?
The primary source of energy for the Earth’s heat budget is the Sun. Solar radiation, or sunlight, is the incoming shortwave radiation that provides the energy needed for various Earth processes.
How is solar radiation distributed on Earth?
Solar radiation is not evenly distributed across the Earth’s surface. The angle of sunlight varies with latitude, causing variations in solar intensity. The equator receives more direct sunlight than the poles.
What happens to incoming solar radiation?
When solar radiation reaches the Earth, it can be reflected, absorbed, or transmitted. Some is reflected back into space by clouds, atmospheric particles, and Earth’s surface. The remainder is absorbed by the atmosphere and Earth’s surface, warming the planet.
How does the Earth release heat?
The Earth releases heat through outgoing longwave radiation, also known as thermal radiation. This is infrared radiation emitted by the Earth’s surface in response to its warming by incoming solar radiation.
How is the Earth’s heat budget related to climate change?
Human activities, particularly the burning of fossil fuels, have increased the concentration of greenhouse gases in the atmosphere. This enhanced greenhouse effect contributes to global warming, altering the Earth’s heat budget and leading to climate change.
What is the role of clouds in the heat budget?
Clouds can both reflect incoming solar radiation (albedo effect) and trap outgoing long wave radiation. The net effect of clouds on the heat budget depends on factors such as cloud type, altitude, and thickness.