Final answer:
The value of 1372 watts per square meter refers to the solar irradiance at the top of Earth's atmosphere, also known as the solar constant. An example calculation demonstrates how to determine the energy absorbed by a solar collector from sunlight.
Step-by-step explanation:
The value of 1372 watts per square meter (or 2 calories per cm² per minute) refers to the solar radiance at the top of Earth's atmosphere. This measurement is often referred to as the solar constant, although it may vary slightly over time. The energy from the Sun, known as solar irradiance, is about 1360 W/m² upon reaching the Earth's atmosphere. About 30% of this is reflected back into space, while the rest is absorbed by the Earth's surface, atmosphere, and clouds, driving the Earth's climate and weather systems.
Example Calculation
Let's calculate the amount of energy that falls on a solar collector with an area of 0.500 m² in a span of 4 hours:
- Intensity of sunlight on Earth's surface: about 700 W/m²
- Energy absorbed in 1 second = 700 watts (since watts are J/s)
- Energy absorbed in 4 hours = 700 W × 4 h × 3600 s/h = 10,080,000 J or 10.08 MJ (mega joules.
The solar radiance plays a significant role in calculations regarding renewable energy, climate studies, and understanding the Earth's energy budget.