Question

The zone which extends above troposphere up to \(50 \mathrm{~km}\) above sea level and contains dinitrogen, dioxygen, ozone and little water vapour is called (a) exosphere (b) mesosphere (c) ionosphere (d) stratosphere.

Short answer

The correct answer is (d) stratosphere.

Step-by-step solution

Understanding the Layers of the Atmosphere

The Earth's atmosphere is divided into several layers, each with distinct characteristics. The troposphere is the layer closest to Earth's surface where we live and where weather happens. Above the troposphere is the stratosphere, which extends from about 10 to 50 km above sea level. This layer contains the ozone layer which absorbs and scatters ultraviolet solar radiation.

Identifying the Correct Zone

The region described in the exercise is directly above the troposphere and extends up to 50 km above sea level. This region is characterized by the presence of dinitrogen, dioxygen, ozone, and little water vapor which matches the description of the stratosphere.

Selecting the Correct Answer

Based on the characteristics provided in the exercise, the correct answer is the one that corresponds to the layer of the atmosphere that exists from the top of the troposphere up to 50 km and contains ozone. Comparing the options provided, the stratosphere is the layer that fits this description.

Key concepts

Atmospheric Layers

The Earth's atmosphere is a complex system consisting of distinct layers, each playing a critical role in supporting life and regulating the planet's climate. Imagine the atmosphere as a multi-level cake, and each layer would represent a different flavor with unique ingredients that characterize it.

Starting from the ground and moving upwards, the first layer we encounter is the troposphere, which reaches up to about 8 to 15 kilometers high. Here, we experience the daily weather patterns and life as we know it. Next, is the stratosphere, extending from the top of the troposphere to about 50 kilometers above Earth. Not only does the stratosphere contain the essential ozone layer, but the air is also drier and less dense, making most of the clouds and weather patterns we're familiar with absent in this zone. More exotic atmospheric layers include the mesosphere, thermosphere, and exosphere, each with increasing altitude and decreasing air density, where phenomena such as meteors burning up or auroras occur.

Understanding the atmospheric layers is fundamental to grasping how various phenomena like atmospheric circulation, the greenhouse effect, and protection from ultraviolet light function. It’s essential for students aiming to comprehend the dynamics of Earth's atmosphere and its impacts on the environment and climate.

Troposphere

The troposphere is, quite literally, the ground floor of Earth's atmospheric layers. Stretching from the Earth's surface up to heights between 8 and 15 kilometers, depending on geographic location and weather conditions, the troposphere is characterized by a decrease in temperature with altitude. This tendency is why mountaintops are often snow-capped while the base is bathed in warmth.

In this bustling layer, we find the air we breathe, consisting of approximately 78% nitrogen and 21% oxygen with traces of other gases. Life's rich tapestry, from hummingbirds to skyscrapers, exists within this atmospheric floor. Moreover, most of the phenomena that constitute our daily weather—like rain, snow, storms, and wind systems—take place here. These weather patterns are driven by the temperature variations and the heat received from the sun, making the troposphere the engine room of Earth's climate system. For students studying meteorology or Earth sciences, grasping the workings of the troposphere is essential for understanding everything from local weather forecasts to global climate change.

Ozone Layer

Perched in the stratosphere, like a protective umbrella shielding us from the sun's potentially harmful ultraviolet radiation, lies the ozone layer. This layer is located approximately 15 to 35 kilometers above Earth and contains a high concentration of ozone (O3) molecules.

While oxygen (O2) is crucial for breathing, ozone plays its part by absorbing the majority of the sun's ultraviolet (UV) radiation, which if not regulated, could lead to increased rates of skin cancer and cataracts, as well as affecting plant life and marine ecosystems. The science behind the ozone layer is fascinating; it’s formed when ultraviolet light hits molecular oxygen (O2), splitting it into individual oxygen atoms. These atoms then join with unbroken O2 to form ozone (O3). This ongoing process, known as the ozone-oxygen cycle, is crucial for life on Earth.

Unfortunately, human activities have led to the depletion of the ozone layer, famously resulting in an 'ozone hole' over Antarctica. The discussion around the ozone layer often brings students into more significant conversations about environmental protection, climate change, and the impact of chemicals like chlorofluorocarbons (CFCs) on Earth's delicate atmospheric balance.