Mini lezione: l'effetto serra | Prof Scienza YouTube Video Summary
This mini-lesson video by Prof Scienza explains the greenhouse effect, defining it as a characteristic of the Earth's atmosphere that enables life on the planet. The video explains how the atmosphere behaves like a greenhouse, trapping solar radiation to maintain a stable temperature, and identifies key greenhouse gasses, including water vapor, carbon dioxide, and methane. The video discusses how excessive greenhouse gasses can cause climate change and negatively impact the Earth.
Detailed Summary:
What is the Greenhouse Effect?
The Prof Scienza mini-lesson focuses on the greenhouse effect and why it is so important to life on Earth. The greenhouse effect is a natural process that warms the Earth's surface, and it is one of the features of our atmosphere that allows life to survive on our planet. The name greenhouse effect comes from the fact that the atmosphere acts like a greenhouse for plants.
How the Greenhouse Effect Works
The atmosphere of our planet behaves like a greenhouse for plants. A greenhouse for cultivating plants allows solar radiation to enter, but it prevents it from exiting. In this way, there is a higher temperature inside of the greenhouse than in the external environment. The atmosphere functions in the same way, but instead of the glass in a greenhouse that traps solar radiation, we have greenhouse gasses. Greenhouse gasses are water vapor, carbon dioxide, and methane.
When radiation strikes a celestial body and is reflected, in part, it is modified, as if it were slowed, and it transforms into infrared radiation, meaning heat. As an example, Prof Scienza uses the moon. When solar radiation reaches the surface of the moon, a celestial body that is without an atmosphere, it is, in part, absorbed, and in part, it is reflected and sent anew into space in the form of light and heat. This is why from Earth we can see the moon. If a celestial body has an atmosphere, as in the case of the Earth, the situation is more complicated.
Of all of the solar radiation that strikes our planet, approximately 55% is immediately reflected from the atmosphere and clouds and is sent into space before it can reach the surface of the planet. The remaining 45% manages to reach the surface. Of this 45%, a part is absorbed by the sea, the plants, the rocks, the soil, etc. However, much of this radiation is reflected toward space. Of all the energy that our planet releases, only 35% exits the atmosphere under the form of heat and dissipates into space. The remaining 65% remains trapped inside the atmosphere because the greenhouse gasses impede the energy from exiting.
The fact that this energy remains trapped inside the atmosphere causes the temperature of the planet to be higher than what it would be in the absence of these greenhouse gasses. If the Earth did not have an atmosphere rich in these gasses, it would have a temperature too low, or too high, and there could not be any living organisms. In fact, the presence of the greenhouse effect allows our planet to have scarce thermal excursion between the day and the night, which is a fundamental factor for the survival of living beings. The moon, however, which has no atmosphere, when illuminated by the sun, since there is no atmosphere to reflect the solar radiation, the temperature is 120 °C - too high to survive.
The Negative Side of the Greenhouse Effect
The greenhouse effect is fundamental for life on our planet, but in the past few years, it has been discussed in a negative way. This is because scientists have discovered that human activities that introduce greenhouse gasses into the atmosphere, increasing their concentration, are causing an excessive increase of the temperature. Too many greenhouse gasses in the atmosphere impede solar radiation from exiting, causing the climate change.