What are the main factors affecting Earth's temperature?

The main factors affecting Earth's temperature are solar radiation, greenhouse gases, Earth's albedo, and atmospheric circulation.

Solar radiation is the primary source of energy for Earth. The Sun emits energy in the form of light and heat, which reaches Earth and warms its surface. The amount of solar energy Earth receives can vary due to changes in the Sun's activity and Earth's orbit around the Sun. These variations can lead to changes in Earth's climate over long periods.

Greenhouse gases, such as carbon dioxide (CO₂), methane (CH₄), and water vapour (H₂O), play a crucial role in regulating Earth's temperature. These gases trap heat in the atmosphere through the greenhouse effect. When solar radiation reaches Earth, it is absorbed by the surface and then re-emitted as infrared radiation. Greenhouse gases absorb this infrared radiation and re-radiate it in all directions, including back towards Earth's surface, keeping the planet warmer than it would be otherwise.

Earth's albedo, or reflectivity, also affects its temperature. Albedo is the measure of how much sunlight is reflected by Earth's surface. Surfaces like ice and snow have high albedo and reflect most of the sunlight, while darker surfaces like oceans and forests have low albedo and absorb more sunlight. Changes in Earth's albedo, such as melting ice caps or deforestation, can lead to changes in the amount of solar energy absorbed, thus affecting the temperature.

Atmospheric circulation, including wind patterns and ocean currents, helps distribute heat around the planet. The movement of air and water transports warm and cold temperatures across different regions, influencing local climates. For example, the Gulf Stream carries warm water from the Gulf of Mexico to the North Atlantic, affecting the climate of Western Europe.

By understanding these factors, we can better analyse how human activities and natural processes influence Earth's climate and temperature.