Uniformity of Emitted Solar Radiation Across the Earth: Strength, Power, and Real-World Implications

Author:
GM Shahzad
Research Scholar
Director, Qalim Institute
Quranic Arabic Research Scholar | Discoverer of Islamic Meditation for Healing | Theorist of Al-Asr Dynamic Number System (ADNS)

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Abstract

The Sun emits electromagnetic radiation uniformly in all directions into space, including toward Earth. While the total solar radiation is isotropic, its received strength (irradiance) varies across Earth’s surface due to factors such as Earth’s curvature, axial tilt, atmosphere, latitude, and time of day. This paper explores whether the Sun’s emitted radiations are of equal strength across different locations on Earth and explains how local conditions modulate solar energy availability. The focus includes the physics of solar irradiance, real-world solar energy potential, and how these variations are harnessed for power generation in different parts of the globe.

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1. Introduction

The Sun, a near-perfect blackbody, emits electromagnetic radiation continuously. At the core of climate systems, photosynthesis, and renewable energy technologies is the principle that all parts of Earth are illuminated by the same Sun — but not equally at the surface level.

This raises a foundational question:

Are the Sun’s emitted radiations of the same strength and power across all regions of Earth?

This paper explores the emission uniformity, atmospheric modulation, and real-life distribution of solar radiation.

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2. Solar Radiation Emission: Constant and Isotropic

2.1 Emission Characteristics

• The Sun radiates energy uniformly in all directions (isotropic emission).

• Total solar power output (solar luminosity):

  $$L = 3.846 \times 10^{26} \, \text{watts}$$

• Radiation travels through space as photons in the form of electromagnetic waves — visible, UV, infrared, X-rays, etc.

2.2 Solar Constant

• At the top of Earth’s atmosphere, average solar irradiance is:

  $$S_0 = 1361 \, \text{W/m}^2$$

• This value is the same globally at the top of the atmosphere and forms the baseline for Earth’s solar energy.

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3. Why Solar Energy Reaches Earth Differently

While the emission from the Sun is uniform, what Earth receives depends on several physical factors.

3.1 Earth’s Curvature and Latitude

• Equatorial regions receive direct overhead sunlight.

• Polar and higher latitude regions receive oblique sunlight over a larger area, reducing intensity.

Region	Average Solar Irradiance (W/m²)
Equator	~1000
Tropics	800–1000
Temperate	600–800
Polar	<400

3.2 Time of Day and Solar Angle

• Solar radiation is highest at solar noon.

• Early morning and late afternoon sunlight has longer path through the atmosphere → greater scattering and absorption.

3.3 Atmospheric Conditions

• Cloud cover, dust, aerosols, and pollution reduce received solar radiation.

• Mountainous or high-altitude areas may receive more sunlight due to thinner atmosphere.

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4. Real-World Solar Energy Applications

4.1 Solar Power in Desert Regions

• Example: Sahara Desert, Saudi Arabia, Arizona

  • Receive >2200 kWh/m²/year

  • Ideal for large-scale solar farms (e.g., Noor Solar Project, Morocco)

4.2 Solar Use in Temperate Countries

• Germany, though less sunny than equatorial regions, is a global leader in rooftop solar energy.

• Effective use of technology (PV efficiency, storage) compensates for moderate irradiance.

4.3 Solar Challenges in Polar Zones

• Months of darkness (polar night) reduce viability.

• Long summer days allow temporary solar generation (e.g., in Alaska, Scandinavia).

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5. The Physics of Equal Emission but Unequal Reception

5.1 Inverse Square Law

Though the Sun emits energy evenly in all directions, distance and angle reduce energy density:

$$I = \frac{P}{4\pi r^2}$$

Where:

• $I$ = irradiance,

• $P$ = total power output,

• $\mathrm{r=\; distance\; from\; source\; (same\; for\; Earth’s\; regions),}$

• angle of incidence changes effective area, not distance.

5.2 Local Insolation Calculation

The daily insolation $H$ is:

$$H = S_0 \cdot \cos(\theta) \cdot t$$

Where:

• $\mathrm{\theta =\; solar\; zenith\; angle,}$

• $\mathrm{t=\; duration\; of\; sunlight.}$

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6. ADNS Insight: A Dynamic Interpretation

In the Al-Asr Dynamic Number System (ADNS):

• The Sun's emission is constant (zero-line event).

• Earth’s surface receives radiation as positive values (+) dynamically shaped by curvature, time, and position.

• Each location on Earth interacts with photons differently, creating localized event domains — highlighting the role of time (Asr) and position in energy perception.

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7. Conclusion

While the Sun emits radiation uniformly, Earth’s geometry and atmosphere lead to significant variation in how much solar energy is actually received at the surface. Thus, emitted solar radiation is equal in strength, but received solar power is unequal due to time, angle, weather, and location. Understanding this distinction is vital for solar engineering, global energy strategy, and climate modeling.

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8. References

1. Duffie, J. A., & Beckman, W. A. (2013). Solar Engineering of Thermal Processes.

2. NASA Earth Observatory.

3. Iqbal, M. (1983). An Introduction to Solar Radiation.

4. NOAA Global Solar Radiation Dataset.

5. Shahzad, G. M. (2025). Al-Asr DNS: Time-Space Reactions and Earth-Sun Relations. Qalim Institute.