EDITOR’S NOTE: Part 2 of a series
Weather isn’t just restricted to the ground. The air above us is filled with its own set of conditions. There are a variety of different atmospheric layers, and some layers are more interesting than others.
The first part of our journey focused on the layers of the atmosphere and some of the important components in our planet’s atmospheric system. Here, we will begin our ascent and examine the different layers that make up the system.
The good thing about being a meteorologist is that we spend a lot of time in the part of the system that we study, which is why I love being a meteorologist. The troposphere is home to a lot of the conditions that make up our weather system.
As I mentioned before, almost all the weather conditions that we observe are in this layer and it plays a big role in the formation of clouds. The height of the troposphere plays a role in climate and average temperatures of different regions. Clouds help trap and reflect the sun’s rays, so we sometimes experience different conditions at different latitudes.
The height of the troposphere tends to be deeper over the equator and shallower at the poles. The seasonal change in climate affects the depth as well, with the troposphere being deeper in the summer and shallower in the winter.
This means that the top of our atmosphere, which is responsible for the formation of weather around the planet, does not conform to a rigid, spherical shape surrounding the planet. It has undulations. There are many factors that contribute to these undulations such as latitude, average temperatures, seasons, and other characteristics of the atmosphere. There is a boundary at the top of the troposphere that is called the tropopause. This boundary is important to weather.
As we climb through the troposphere, the temperature decreases. This is known as the environmental lapse rate. This rate varies and is dependent on the conditions of the atmosphere and the moisture it contains. On average the environmental lapse rate is about 3.5°F per 1,000 feet.
The cooling of the air is a result of the atmosphere being in contact with the hot surface of the planet. As the air rises, it loses heat and becomes even cooler. It is this process that leads to the formation of clouds. This process is also the cause of precipitation and other activities in the atmosphere.
During your day-to-day activities you may have noticed the cooling of the atmosphere without realizing it. While driving, you may have noticed cooling as you went from the valley to the mountains. While flying in an airplane, the temperature outside the plane may have been well below zero, especially if the airplane was cruising at a high altitude. The temperature at the airport may have been in the 90s.
Most of the water vapor in the atmosphere is found in the troposphere. This is the primary reason for the existence of weather in this region. Water is always in movement between the surface of the earth and the atmosphere. This is accomplished through various processes of the water cycle. Rising of air and subsequent cooling is the reason for the formation of clouds. Under various conditions clouds can lead to the formation of different types of precipitation.
Among all the cycle and processes that lead to the formation of weather, the one that is of primary interest to weather enthusiasts and especially those who have interest in severe weather, is the one that leads to the development of thunderstorms. As in the case of formation of all other types of storms, development of a thunderstorm begins with rising of air in the lower region of the atmosphere. If the air is unstable, then moist air rises, cools and condensates to form clouds. The continued rise of moist air can lead to the development of cumulonimbus clouds that can be extremely tall.
The development of a thunderstorm can lead to attaining of the tropopause. At the tropopause, the air can spread laterally and lead to the development of the characteristic head of a radiation cloud. Thunderstorms can also lead to the development of an Overshooting top. An Overshooting top is the temporary condition that exists when the upward air flow of a thunderstorm can extend into the lower stratospheric air. As a meteorologist, the presence of an overshooting top during severe weather conditions creates great interest as it signifies the presence of an extremely strong and tall thunderstorm.
The troposphere is the lowest layer of the atmosphere. Storms are generated in this layer. The movement of large-scale systems in this layer causes regional variation in weather. Complex movements of air masses in this layer give rise to features such as low- and high-pressure systems, cold and warm fronts and others.
In the upper regions of the troposphere, jet streams, another important feature in Meteorology, are found. Jet streams are high altitude winds which can attain speeds of 100-200 mph. Jet streams play an important role in steering and shifting weather systems.
Jet streams also affect the displacement of air masses over a region. Jet streams have a wavy and uneven nature. The undulating nature of the jet stream impacts the intensity of weather systems on the surface.
Troposphere is nearest to the Earth’s surface and contains 80-85% of the atmosphere by mass. As one moves up from the Earth’s surface, the weight of overlying atmosphere decreases, causing a decrease in air pressure. Increased altitude causes a decrease in density and viscosity of the gaseous constituents of the atmosphere. Hence, at high altitudes, gases do not transfer heat efficiently. This is why high-altitude mountaineers suffer from hypothermia.
The troposphere is the name for the atmospheric zone in which we find weather. This zone surrounds the entire planet. Because the planet is roughly 8,000 miles in diameter, the troposphere isn’t very deep. The huge-looking clouds that roll by have all of their masses contained within this relatively shallow zone of the atmosphere. Also within this zone are powerful storms which, when viewed from the ground, appear to be very large. The same is true of hurricanes. From an artistic viewpoint, imagine how different a painting of a hurricane would be if the entire hurricane (and not just a small portion of it) was depicted.
While standing at a window, one can look directly into the troposphere and watch the ever-changing formations and patterns that are caused by the actions of the atmospheric agents. The interactive nature of the various agents of the lower zone of the atmosphere give rise to the various and continually evolving forms of weather.
