Which of the following statements regarding insolation is/are correct?

1. Insolation is predominantly short- wave radiation, with wavelengths in the range of 0.39 micrometre to 0.76 micrometre.

2. Insolation is evenly distributed across the Earth because of the Earth's curved surface.

Select the correct answer using the code given below. 

The correct answer is 1 only.

Key PointsInsolation

• Insolation, or incoming solar radiation, refers to the solar energy that reaches the Earth's surface. It is a critical factor driving weather patterns and climate.
• The statement that insolation is predominantly short-wave radiation, with wavelengths in the range of 0.39 micrometre to 0.76 micrometre, is accurate. This range includes the visible spectrum, which is a significant portion of the solar radiation that reaches and warms the Earth. Hence, statement 1 is correct.
• The claim that insolation is evenly distributed across the Earth because of the Earth's curved surface is incorrect. The Earth's curvature, axial tilt, and orbital eccentricities result in uneven distribution of solar energy, with the equatorial regions receiving more insolation than polar regions. This uneven distribution is a fundamental cause of climate zones and seasonal changes. Hence, statement 2 is incorrect.

Additional Information

• Solar Radiation: The sun emits energy in the form of electromagnetic radiation. When this radiation travels through space and reaches the Earth's atmosphere and surface, it is referred to as solar radiation or insolation.
• Wavelengths of Solar Radiation: The solar spectrum includes not only visible light but also ultraviolet (UV) and infrared (IR) radiation. UV radiation has shorter wavelengths than visible light, whereas IR radiation has longer wavelengths.
• Effects of Insolation: The amount of insolation received by different parts of the Earth influences climate patterns, weather conditions, and the growth of vegetation. It is also a key factor in the Earth's energy balance, affecting temperature and atmospheric circulation.
• Seasonal Variations: The Earth's tilt and its orbit around the sun lead to variations in the angle at which the sun's rays strike the Earth, causing seasons. This results in significant changes in insolation over the course of a year for most locations.
• Latitude and Insolation: Insolation varies with latitude, with equatorial regions receiving more consistent and direct sunlight year-round compared to higher latitudes, which experience more pronounced seasonal variations.