11.1 Earth And The Atmosphere

Explanation
The air we breathe is made of 78% nitrogen. Nitrogen is the most abundant gas in the Earth's atmosphere, making up a significant portion of the air we breathe. It is an essential component for many biological processes and is also used in various industrial applications. Oxygen, although important for respiration, only makes up about 21% of the air we breathe. Argon, neon, and carbon dioxide are present in much smaller quantities.

Explanation
The mesosphere is the layer of the Earth's atmosphere located above the stratosphere and below the thermosphere. It is known to contain the coldest temperatures known to man. The temperatures in this layer can drop as low as -90 degrees Celsius (-130 degrees Fahrenheit). This is due to the thinness of the air and the lack of heat-trapping gases. The mesosphere is also the layer where meteors burn up upon entering the Earth's atmosphere.

Explanation
The troposphere is the lowest layer of the atmosphere, extending from the Earth's surface up to about 10-15 kilometers. It is characterized by a decrease in temperature with increasing altitude. This layer contains the greatest number of air molecules compared to the other layers of the atmosphere. As we move higher up in the atmosphere, the density of air molecules decreases. Therefore, the troposphere is the layer where most of the Earth's weather occurs, as it is the layer where the majority of air molecules are present.

Explanation
The exosphere is the outermost layer of the Earth's atmosphere and is located above the thermosphere. It extends from about 500 kilometers above the Earth's surface to the edge of space. It is considered the deepest layer because it is the farthest from the Earth's surface. The exosphere is characterized by extremely low density and contains very few particles. It is where satellites and other spacecraft orbit the Earth.

Explanation
Water vapor is a gas that is constantly changing in the atmosphere due to weather conditions and location. It can exist in the form of invisible gas or as visible clouds, depending on factors such as temperature and humidity. Water vapor plays a crucial role in the Earth's weather system, as it can condense to form clouds and precipitation. Its concentration in the atmosphere varies greatly, making it a dynamic component of the Earth's atmosphere.