Radiation and Climate — Lesson 1

This lesson covers the concept of radiative heat transfer and its significant role in Earth's climate. It explains how the balance between solar radiation absorbed by the Earth and radiation emitted by the Earth to space maintains the Earth's mean temperature. The lesson further discusses the impact of the Sun's radiation, known as the solar constant, and how it varies with seasons. It also delves into the concept of the greenhouse effect, explaining how certain gases in the Earth's atmosphere absorb the Earth's emitted radiation, leading to an increase in the Earth's surface temperature. The lesson concludes by discussing the potential future implications of increased carbon dioxide levels due to human activities.

Video Highlights

02:15 - Discussion on the solar constant and the radiation normal to the Sun’s rays at the mean Earth-Sun distance
07:49 - Explanation of the effective black body temperature of the Earth and Greenhouse effect
17:17 - Discussion on the role of minor gases like water vapor, carbon dioxide, methane, nitrous oxide, chlorofluorocarbon in the Earth's climate
25:24 - Explanation of the simple model of the Earth's atmosphere and its impact on the Earth's surface temperature
37:55 - Discussion on the sensitivity of the Earth's climate to small changes in the incoming solar radiation, the Earth's albedo, or the emissivity of the atmosphere
49:31 - Discussion on the potential future impact of burning coal, oil, and natural gas on the Earth's temperature

Key Takeaways

- The Earth's mean temperature is maintained by the balance between solar radiation absorbed by the Earth and radiation emitted by the Earth to space.
- The solar constant, the radiation arriving from the Sun, varies with seasons due to the Earth's elliptical orbit around the Sun.
- Certain gases in the Earth's atmosphere, such as water vapor, carbon dioxide, and methane, absorb the Earth's emitted radiation, leading to an increase in the Earth's surface temperature - a phenomenon known as the greenhouse effect.
- Increased carbon dioxide levels due to human activities could potentially lead to a significant increase in the Earth's surface temperature in the future.