Light photons and infrared photons exhibit distinct characteristics and behaviors. Light photons, emitted by the Sun as short-wave radiation, enter the Earth’s atmosphere and interact with the surface.
These photons can either be absorbed or reflected. The reflected photons become infrared, with longer wavelengths and lower energy than visible light. As these infrared photons ascend through the atmosphere, they may either pass through unimpeded or interact with other molecules.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
Unlike particles, infrared photons behave as waves and can propagate through radiation rather than conduction or convection. This unique property allows them to flow through the atmosphere. When light photons reach the Earth, they are absorbed by the surface or reflected.
If the photons are interested, they transfer their energy to the surface, generating heat energy that warms the surface. This absorption process contributes to the temperature increase on Earth.
On the other hand, if the photons are reflected, they can re-enter the atmosphere without releasing their energy. These reflected photons continue their journey through the atmosphere, interacting with various components such as gases, aerosols, and clouds.
Additionally, these photons may collide with molecules in the atmosphere, such as carbon dioxide (CO2) or water vapor (H2O), transferring energy to them. When photons interact with molecules, the molecules absorb the energy and become excited. As a result, the temperature of the surrounding air increases.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
The energized molecules subsequently emit the absorbed energy in the form of photons, which can either escape into space or be absorbed by other molecules, perpetuating the process. This continuous absorption and re-emission of photons contribute to heating the Earth’s surface, as the energy remains within the atmosphere instead of escaping back into space.
Clouds play a significant role in altering the path of photons from the Sun to the Earth. Clouds consist of water droplets or ice crystals suspended in the atmosphere. They reflect a substantial portion of the Sun’s radiation, preventing it from reaching the surface directly. The cloud particles scatter and redirect the incoming solar radiation in different directions. This scattering effect reduces the amount of solar energy that comes to the surface, resulting in a cooling effect.
Furthermore, clouds also reflect the energy emitted by the Earth’s surface back into the atmosphere. This process is known as the “cloud-albedo effect.” Clouds act as mirrors, reflecting the thermal radiation emitted by the Earth’s surface.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
This cycle of reflection between clouds and the surface traps heat energy, impeding its escape into the atmosphere. The trapped energy contributes to the warming of the lower atmosphere and plays a crucial role in regulating the Earth’s temperature.
Greenhouse gases, including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor (H2O), are naturally present in the Earth’s atmosphere. Greenhouse gases significantly impact the infrared photons reflected from the Earth’s surface.
When infrared waves are reflected into the atmosphere from the Earth’s surface, greenhouse gases absorb them. This absorption occurs due to the specific molecular structure of these gases, which allows them to interact with infrared radiation.
Greenhouse gases act as a natural “blanket” around the Earth, trapping heat and preventing it from escaping into space. Once greenhouse gases absorb infrared photons, they become energized. The energized molecules subsequently re-emit the absorbed energy within the atmosphere.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
Some of these photons are absorbed by other molecules, further releasing energy, while some escape into space without exerting their power. This continuous cycle of absorption and emission contributes to energy recycling within the atmosphere, leading to its heating. This phenomenon is known as the greenhouse effect.
The microscopic evidence from the photon absorption model supports the idea that greenhouse gases play a crucial role in the absorption and re-emission of infrared photons. In the model, infrared photons are observed.
They are being released or reflected into the atmosphere, where greenhouse gases await to absorb them. The absorption process occurs when the energy levels of greenhouse gas molecules match the energy of the incoming photons.
Once absorbed, the greenhouse gases become excited and emit the point in the form of another photon, which can continue the cycle. This microscopic evidence confirms that greenhouse gases act as absorbers and emitters of infrared photons.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
The composition of greenhouse gases in the atmosphere determines their ability to absorb infrared radiation. For example, carbon dioxide (CO2), nitrogen (N2), water vapor (H2O), oxygen (O2), and methane (CH4) molecules can absorb and emit infrared photons.
These molecules act like sponges, selectively absorbing photons based on their readiness to absorb. When these molecules are “full,” the photons pass right by them. However, when they are ready to drink, they absorb the photons, become excited, and release them in any direction. This absorption and emission process causes the atmosphere to heat up as the energy from the molecules keeps getting recycled.
The temperature difference between the inside of a building or car and the outside environment can be explained by the enclosed nature of these spaces. When light energy enters through windows, it becomes trapped inside and cannot escape easily.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
The trapped energy bounces around within the confined space, continuously interacting with the air molecules. As the photons transfer their power to the air molecules, they become excited and heat the surrounding air.
The heated air then emits its photons, which other molecules absorb, initiating a repeated cycle. Since there is no significant exchange of air between the enclosed space and the outside environment, the energy accumulation within the confined space leads to a difference in temperature, making the inside of the building or car sometimes warmer than the outside.
The greenhouse effect plays a vital role in a planet’s habitability. Greenhouse gases in the Earth’s atmosphere absorb and re-radiate heat energy in all directions. This process involves photons being absorbed, scattered, and re-emitted within the atmosphere.
Approximately half of the incoming light from the Sun is absorbed by the land, plants, and animals. Once absorbed, this energy is released back into the atmosphere as thermal radiation, primarily in the form of carbon dioxide (CO2), which acts as one of the greenhouse gases.
PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
The greenhouse effect is essential for maintaining a suitable temperature range for sustaining life on Earth. Without this effect, heat would rapidly dissipate into space, making the planet inhospitably cold. The combination of various gases in the atmosphere, including CO2, helps maintain the Earth’s temperature and stability, providing a suitable environment for life as we know it.
In conclusion, the behavior of light and infrared photons has significant implications for Earth’s temperature and climate. Light photons are absorbed or reflected upon reaching the Earth’s surface, while infrared photons propagate through the atmosphere, interacting with molecules and contributing to the heating of the atmosphere.
Clouds alter the path of photons, reflecting solar radiation and emitting thermal radiation. Greenhouse gases, such as carbon dioxide and water vapor, absorb and re-emit infrared photons, leading to the atmosphere’s greenhouse effect and heat retention. Understanding these processes is crucial for comprehending Earth’s climate dynamics and the impact of human activities on the planet’s habitability. PHY 1000 Unit 4 Assignment 1 Greenhouse Effects
References
Airapetian, V. S. (2014). Rocking stories of the universe. Dubuque, IA: Great River Learning.
Glickstein, I. (2011). Visualizing the “Greenhouse Effect” – Molecules and Photons. Retrieved from Wattsupwiththat:
Visualizing the "Greenhouse Effect" – Molecules and Photons
PHET. (2016). The Greenhouse Effect. Retrieved from PhET Interactive Simulations:
