The concept of the Heat Budget of Earth refers to the perfect balance of the heat that the Earth is absorbing and the heat escaping from the Earth. This process takes place in the form of radiation. This explains the Earth's constant temperature despite the massive transfer of heat.
Heat Budget of Earth - Overview
Consider that we receive a hundred percent of isolation at the topmost layer of the atmosphere. Some of the energy is reflected, some are absorbed, and some are scattered. Only a part of this energy reaches the Earth.
Roughly the amount of energy reflected back to space is 35 units, 27 units of energy are reflected from the clouds, and areas that are covered with ice of the Earth reflect two units. This amount of reflected radiation is defined as the Albedo of the Earth.
48 units are being absorbed by the atmosphere and are a part of it is also radiated back to space. Hence, the total amount of radiation that returns from the Earth is around 65 units. The perfect balance of both incoming and outgoing heat forms the stable Heat Budget of Earth.
Earth's Energy and its Connection to the Heat Budget of Earth
To understand the heat budget, it is important to know the basics of the earth's energy flow. Despite the enormous transfer of energy in and out of the Earth, the Earth maintains its constant temperature because, as a whole, there is no net gain or loss. This is because the Earth emits the same amount of energy as it receives. This crucial mechanism forms the foundation of the Heat Budget of Earth.
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Heat Budget of Earth - Incoming Solar Energy
The total amount of energy received on Earth per second at the top of the Earth's atmosphere is called Incoming solar energy. This is added to the total value of the heat budget. It is also called short-wave radiation. It is measured in watts. The Earth's sphere shape receives the approximate amount of 340 watts per square meter. Also, the amount of energy absorbed varies with location.
Out of this 340 watts per meter square, 77 watts per metre square is reflected back to space by clouds and the surface of the Earth, and the rest 240-metre square is added to Earth's solar energy budget. This amount is called absorbed solar radiation.
Outgoing Solar Energy and its Impact on the Heat Budget of Earth
The total amount of energy leaving the Earth is called outgoing solar energy. It is also called longwave radiation. Energy absorbed is converted into different forms of heat energy, and some of it is emitted out of space in the form of OLR (outgoing longwave radiation). This energy is subtracted from the total energy value in the heat budget of the earth.
We can say that Earth receives a certain amount of insolation in the form of short waves and gives back heat in the form of longwave radiations, and through this, the Earth can maintain its temperature, and consequently, a constant Heat Budget of Earth.
Earth's energy is governed by the first law of Thermodynamics, which states that energy cannot be created nor destroyed.
FAQs on Heat Budget of Earth
Q.1. Which two factors can disturb the heat budget of the Earth?
Global Warming and Climate Forcings are the two factors that can disturb the Heat Budget of Earth.
Q.2. How much percentage of heat is absorbed by the Earth? How does this impact the Heat Budget of Earth?
The Earth absorbs 70% of incoming radiation. This radiation is not reflected back and therefore not deducted from the Heat Budget of Earth.
Q.3. Name the factors that impact the Heat Budget of Earth.
The factors that impact the Heat Budget of Earth are -
- Atmospheric aerosols
- Land use methods
- Greenhouse gases
Q.4. Which three processes take place during the Heat Budget of Earth?
Three processes that take place during the Heat Budget of Earth are -