Insolation

Understanding Insolation

• Insolation refers to the amount of solar radiation received on a given surface area in a given time. It is primarily responsible for the Earth’s weather and climate.
• It is derived from ‘incoming solar radiation’ and is measured in ‘solar energy per square metre per second’.
• Solar radiation contains light, heat and ultraviolet rays. Ultraviolet rays can be harmful, but the Earth’s atmosphere absorbs most of this radiation.

Factors Affecting Insolation

• The angle of incidence: Sun rays at a higher incidence angle cover more area and, consequently, the energy gets dispersed. This difference causes the poles to be colder compared to the equator.
• The Earth’s tilt: The tilt of Earth on its axis affects the angle of incidence. During different seasons, either the northern or southern hemisphere gets more sunlight.
• Day length: The number of daylight hours impacts how much solar radiation a location gets in a day.

Impacts of Insolation

• Affects weather and climate conditions. Areas receiving high insolation experience hotter climates.
• Determines seasonal changes, influencing ecosystems and human activities.
• Powers the water cycle by evaporating water from the Earth’s surface.
• Provides energy for photosynthesis, the process through which plants convert solar energy into food.

Insolation and the Earth’s Energy Balance

• The Earth’s energy budget involves a balance between incoming insolation and outgoing radiation.
• Albedo is the reflectivity of the Earth’s surface. Snow and ice have a high albedo and reflect more sunlight, while darker surfaces absorb more sunlight.
• Greenhouse effect is the trapping of heat in the Earth’s atmosphere by greenhouse gases. This helps maintain the Earth’s temperature and supports life.
• Anthropogenic activities increasing levels of greenhouse gases, disrupt this balance, leading to global warming.