The troposphere contains about three quarters of the mass of the entire atmosphere. The troposphere is only 12 km thick while the whole atmosphere is about 120 km thick. Explain why the troposphere contains such a large fraction of the total mass.

Verified step by step guidance

insert step 1: Understand that the troposphere is the lowest layer of Earth's atmosphere, where most of the atmospheric mass is concentrated.

insert step 2: Recognize that the troposphere is denser than the layers above it due to the gravitational pull of Earth, which causes air molecules to be more tightly packed at lower altitudes.

insert step 3: Consider that the troposphere contains most of the water vapor and weather phenomena, contributing to its mass.

insert step 4: Note that the pressure decreases with altitude, meaning that the air is less dense in the higher layers of the atmosphere, such as the stratosphere and beyond.

insert step 5: Conclude that the combination of higher density, presence of water vapor, and gravitational effects results in the troposphere containing about three quarters of the atmospheric mass despite its relatively small thickness.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Atmospheric Composition

The atmosphere is composed of various gases, primarily nitrogen (78%) and oxygen (21%), with trace amounts of other gases. The distribution of these gases is not uniform; most of the mass is concentrated in the lower layers, particularly the troposphere, due to gravitational forces that hold denser gases closer to the Earth's surface.

Pressure and Density

Atmospheric pressure decreases with altitude, leading to a corresponding decrease in gas density. In the troposphere, the pressure is highest, resulting in greater density and, consequently, a larger mass of air. This phenomenon explains why the troposphere, despite its relatively small thickness, contains a significant portion of the atmosphere's total mass.

Temperature Gradient

The troposphere experiences a temperature decrease with altitude, which affects the behavior of air molecules. Warmer air at lower altitudes is less dense and can hold more moisture, contributing to the mass of the troposphere. This temperature gradient helps maintain a stable layer of air that retains most of the atmosphere's mass.

Recommended video:

Guided course

03:48

Temperature vs Heat

Related Practice

Textbook Question

Name the regions of the atmosphere. What property is used to distinguish between different regions of the atmosphere?

views

Textbook Question

The Earth's atmosphere has a mass of approximately 5.15 * 1015 kg. If the average molar mass of air is 28.8 g/mol, how many moles of gas make up the atmosphere? What is the volume of the atmosphere in liters under conditions of STP? (Note: The average molar mass of air is the weighted average of the molar mass of nitrogen and oxygen. 0.20132.0 g>mol2 + 0.80128.0 g>mol2 = 28.8 g>mol.)

Textbook Question

The percent by volume of oxygen (20.95%) is constant throughout the troposphere. (a) Express this percentage as a mole fraction.