Longwave radiation

Definition

Longwave radiation refers to the infrared radiation emitted by the Earth's surface as it absorbs solar energy and then re-emits it back into the atmosphere. This process plays a crucial role in the Earth's energy balance, as it helps regulate the planet's temperature and influences climate patterns.

5 Must Know Facts For Your Next Test

1. Longwave radiation is primarily associated with temperatures below 4,000 nanometers, where the Earth emits energy after absorbing sunlight.
2. The balance between incoming shortwave radiation and outgoing longwave radiation is essential for maintaining a stable climate on Earth.
3. Greenhouse gases such as carbon dioxide and methane absorb and re-radiate longwave radiation, contributing to the greenhouse effect and global warming.
4. Different surfaces on Earth (like forests, oceans, or deserts) emit longwave radiation at varying rates depending on their temperature and composition.
5. Human activities that increase greenhouse gas concentrations enhance the natural greenhouse effect, leading to more trapped longwave radiation and rising global temperatures.

Review Questions

• How does longwave radiation interact with greenhouse gases in the atmosphere, and what is the significance of this interaction?
  • Longwave radiation interacts with greenhouse gases in the atmosphere by being absorbed and then re-emitted in all directions, including back toward the Earth's surface. This process is significant because it helps maintain the Earth's temperature by preventing heat from escaping into space. The enhanced greenhouse effect caused by increased concentrations of these gases leads to a rise in global temperatures, impacting climate patterns.
• Compare and contrast longwave radiation with shortwave radiation in terms of their roles in Earth's energy balance.
  • Longwave radiation differs from shortwave radiation primarily in its wavelength and source. Shortwave radiation is emitted by the sun and includes visible light that warms the Earth upon absorption. In contrast, longwave radiation is emitted by the Earth itself after it absorbs solar energy. Both types of radiation are crucial for Earth's energy balance; however, while shortwave radiation heats the planet, longwave radiation is vital for cooling through emission back to space.
• Evaluate the impact of increasing atmospheric CO2 levels on longwave radiation and its implications for climate change.
  • Increasing atmospheric CO2 levels enhance the greenhouse effect by trapping more longwave radiation that would otherwise escape into space. This leads to a rise in Earth's average temperature, disrupting climate systems and causing extreme weather events. The implications for climate change include rising sea levels due to melting ice caps, shifts in biodiversity as species adapt or relocate, and increased frequency of heatwaves, ultimately affecting human populations and ecosystems globally.

Related terms

shortwave radiation:

Shortwave radiation includes the higher energy wavelengths of solar radiation, primarily visible light and ultraviolet light, which are absorbed by the Earth’s surface.

greenhouse effect:

The greenhouse effect is the warming of the Earth's surface due to the trapping of longwave radiation by greenhouse gases in the atmosphere.

albedo:

Albedo is a measure of the reflectivity of a surface, which affects how much solar radiation is absorbed or reflected back into space.