"The Earth's atmosphere allows life to exist. . . like a protective bubble that surrounds the planet," stated Ueyama. Although invisible, the atmosphere provides air and shields us from UV rays. It also traps heat, maintaining moderate temperatures. Without it, Earth's temperatures would fluctuate drastically like the moon.
The atmosphere consists of five main layers, each defined by temperature, chemical composition, and air density.
1. Troposphere: The lowest layer, where weather occurs and most atmospheric mass and water vapor are found. The temperature decreases with altitude, causing snow on tall mountains.
2. Stratosphere: Above the troposphere, it has less turbulent air. Commercial aircraft fly here. The temperature increases with altitude due to the ozone layer, which absorbs UV radiation, creating stability.
3. Mesosphere: The middle layer, where meteors burn up due to friction. It's the coldest atmospheric layer because it receives less solar radiation and has less dense air.
4. Thermosphere: Above the mesosphere, it expands and contracts with solar radiation. Temperatures can exceed 2000 C. The International Space Station orbits here. The ionosphere, within the meso- and thermospheres, creates auroras when particles collide.
5. Exosphere: The outermost layer, where most satellites orbit, marking the transition to outer space.
Current topics of interest include greenhouse gases, pollution, air quality, and cloud-related processes. Researchers aim to understand their impact on climate and public health.
Greenhouse Gases: These gases, from natural and human activity, trap heat and increase global temperatures. While necessary for maintaining habitable temperatures, excessive anthropogenic greenhouse gases contribute to climate change.
Pollution/Air Quality: Pollution poses health risks and affects climate. Aerosols from natural and human sources alter the atmosphere's composition, impacting the radiative balance and climate. PM2.5 particles, from sources like vehicle exhaust, can cause health problems.
Clouds: Clouds influence weather and climate. Low clouds cool the Earth, while high clouds trap heat. Understanding these processes helps improve climate models and predictions.
NASA conducts extensive atmospheric research through programs like UARP, TCP, RSP, and ACMAP. The PACE satellite studies the carbon exchange between the ocean and atmosphere, while the INSTEP network monitors air pollution.
Related Links
NASA Atmospheric Science Branch
Earth Observation News - Suppiliers, Technology and Application
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