Heat Budget of the Earth

Energy budgets account for the balance between the amount of energy that Earth receives from sunlight and the amount of energy that the Earth loses back into space. The energy budget also takes into consideration how energy moves through the atmosphere, ocean, land surface, and ice sheets. Solar irradiance is unevenly spread across the globe because the Sun heats the tropical troposphere more than the polar regions. This uneven distribution causes an imbalance in the global energy budget, which drives interactions in the climate system.

Earth’s heat budget depends upon many factors, but primarily on the atmosphere. Greenhouse gases affect Earth’s climate. Clouds influence how much sunlight reaches our planet. Land use affects how plants emit or absorb solar radiation. Aerosols affect cloud formation. Surface reflectivity affects how much sunlight is reflected back into space. Earth’s surface temperature also affects the amount of carbon dioxide in the atmosphere. This causes changes in global temperatures. Over time, these changes cause Earth’s climate to change.

Heat Budget of the Earth and Atmosphere

Global radiation refers to the entire solar radiation that reaches a horizontal surface on the earth. It consists of the sun’s direct shortwave radiation plus the diffuse radiation diffused by the atmosphere. It should be noted that solar energy collected at the Earth’s surface is turned into heat energy, which heats the earth’s outer surface.

As a result, after being heated, the Earth emits energy in the form of longwave radiation. Incoming shortwave solar radiation from the sun is known as incoming shortwave solar radiation, while outgoing longwave terrestrial radiation from the earth is known as outgoing longwave terrestrial radiation.

Earth Energy Budget Equation 

The planet receives 51 units of solar insolation as direct radiation, which may be classified as follows:

1. Received by direct radiation= 34 units
2. Received as diffused daylight= 17 units, for a total of 51 units.

Albedo

Albedo is a measure of how much sunlight reflects off a surface. It is a reflection ratio and has a value of less than one. Albedo for the Earth is different depending on what kind of surface it is. For example, ice has more albedo than sand.

Variation in the Net Budget at the Earth’s Surface

Although the planet as a whole maintains a balance between insolation and terrestrial radiation, we see a distinct picture at different latitudes. As we previously established, the amount of insolation obtained varies depending on latitude. The amount of insolation in the tropical zone is greater than the amount of terrestrial radiation. As a result, it is a hot spot. In the polar regions, heat gain is greater than heat loss. As a result, it is a heat-deficit zone. As a result, insolation causes a heat imbalance at various latitudes.

Variability of Insolation at the Earth’s Surface

The amount and intensity of insolation vary during the day, season, and year. These fluctuations in insolation are caused by the following factors: I the rotation of the earth’s axis; (ii) the angle of incline of the sun’s rays; (iii) the length of the day; (iv) the clarity of the atmosphere; and (v) the configuration of land in terms of its aspect.

The final two, on the other hand, have less clout. The fact that the earth’s axis forms a 66-degree angle with the plane of its orbit around the sun has a bigger impact on the quantity of insolation received at various latitudes.

Heating and Cooling of the Atmosphere

The sun is the ultimate source of heat and energy in the atmosphere. There are several methods for heating and cooling the environment. They are as follows:

1. Radiation 2. Conduction 3. Advection 4. convection

Radiation

The earth absorbs short waves of solar radiation from the sun and then reradiates them into space. This is called Terrestrial Radiation. After this radiation reaches the atmosphere, it heats it from the bottom up. Carbon Dioxide is the most important gas that absorbs the longwave radiation from the atmosphere. As a result, the temperature of the atmosphere increases.

Conduction 

Conduction is the process of transferring heat from a warmer body to a colder body by direct physical contact. Heat flows from the hotter body to the colder body until the two bodies reach the same temperature. Conduction in the atmosphere transfers heat from the hot ground below to the cold upper layer of air above. This causes warming of the air and cooling of the land surface beneath.

Convection 

Convection is when heat is transferred from a hot object (like the sun) to cooler objects around it, usually using a liquid or gas as the medium. This causes the warmer fluid to rise up and cool down. Convective heating occurs within the troposphere. Cooler air rises as warm air descends and cools. This results in convection, and then more convection leads to even more rising air, and so on—eventually, the temperature increases due to this process.

Advection

Advection is the transmission of heat by the horizontal movement of air—winds transport temperature from one location to another. If a location is in the path of warm-weather winds, its temperature will climb. If the location is in the direction of cold-weather winds, the temperature will drop.

The horizontal movement of air is more essential than the vertical movement. The majority of diurnal (day and night) fluctuations in daily weather in the middle latitudes are produced solely by advection. Local winds known as ‘Loo’ are the result of the advection process in tropical locations, notably in northern India during the summer season.

Conclusion 

A heat budget is an exact balance between incoming heat received by the earth and outgoing heat escaping by radiation. If the equilibrium is upset, the planet will gradually get warmer or colder with each passing year.