Temperature inversion

 Temperature inversion layers, also called thermal inversions or just inversion layers, are areas where the normal decrease in air temperature with increasing altitude is reversed and the air above the ground is warmer than the air below it. Inversion layers can occur anywhere from close to ground level up to thousands of feet into the atmosphere.

Inversion layers are significant to meteorology because they block atmospheric flow which causes the air over an area experiencing an inversion to become stable. This can then result in various types of weather patterns.

More importantly, though, areas with heavy pollution are prone to unhealthy air and an increase in smog when an inversion is present because they trap pollutants at ground level instead of circulating them away.

Causes

Normally, air temperature decreases at a rate of 3.5°F for every 1,000 feet (or roughly 6.4°C for every kilometer) you climb into the atmosphere. When this normal cycle is present, it is considered an unstable air mass, and air constantly flows between the warm and cool areas. The air is better able to mix and spread around pollutants.

During an inversion episode, temperatures increase with increasing altitude. The warm inversion layer then acts as a cap and stops atmospheric mixing. This is why inversion layers are called stable air masses.

Temperature inversions are a result of other weather conditions in an area. They occur most often when a warm, less dense air mass moves over a dense, cold air mass.

This can happen, for example, when the air near the ground rapidly loses its heat on a clear night. The ground becomes cooled quickly while the air above it retains the heat the ground was holding during the day.

Temperature inversions also occur in some coastal areas because upwelling of cold water can decrease surface air temperature and the cold air mass stays under warmer ones.

Topography can also play a role in creating a temperature inversion since it can sometimes cause cold air to flow from mountain peaks down into valleys. This cold air then pushes under the warmer air rising from the valley, creating the inversion.

In addition, inversions can also form in areas with significant snow cover because the snow at ground level is cold and its white color reflects almost all heat coming in. Thus, the air above the snow is often warmer because it holds the reflected energy.

Consequences

Some of the most significant consequences of temperature inversions are the extreme weather conditions they can sometimes create. One example is freezing rain.

This phenomenon develops with a temperature inversion in a cold area because snow melts as it moves through the warm inversion layer. The precipitation then continues to fall and passes through the cold layer of air near the ground.

When it moves through this final cold air mass it becomes "super-cooled" (cooled below freezing without becoming solid.) The supercooled drops then become ice when they land on items like cars and trees and the result is freezing rain or an ice storm.

Intense thunderstorms and tornadoes are also associated with inversions because of the intense energy that is released after an inversion blocks an area’s normal convection patterns.

Effects of Acid Rain

 

Effects of Acid Rain

After studying the Hubbard Brook Forest and other areas, researchers found several important effects of acid deposition on both natural and man-made environments. Aquatic settings are the most clearly affected by acid deposition, however, because acidic precipitation falls directly into them. Both dry and wet deposition also runs off from forests, fields, and roads and flows into lakes, rivers, and streams.

As this acidic liquid flows into larger bodies of water, it is diluted. Howvever, over time, acids can accrue and lower the overall pH of the body of water. Acid deposition also causes clay soils to release aluminum and magnesium, further lowering the pH in some areas. If the pH of a lake drops below 4.8, its plants and animals risk death. It is estimated that around 50,000 lakes in the United States and Canada have a pH below normal (about 5.3 for water). Several hundred of these have a pH too low to support any aquatic life.

Aside from aquatic bodies, acid deposition can significantly affect forests. As acid rain falls on trees, it can make them lose their leaves, damage their bark, and stunt their growth. By damaging these parts of the tree, it makes them vulnerable to disease, extreme weather, and insects. Acid falling on a forest’s soil is also harmful because it disrupts soil nutrients, kills microorganisms in the soil, and can sometimes cause a calcium deficiency. Trees at high altitudes are also susceptible to problems induced by acidic cloud cover as the moisture in the clouds blankets them.

Damage to forests by acid rain is seen all over the world, but the most advanced cases are in Eastern Europe. It’s estimated that in Germany and Poland, half of the forests are damaged, while 30 percent in Switzerland have been affected.

Finally, acid deposition also has an effect on architecture and art because of its ability to corrode certain materials. As acid lands on buildings (especially those constructed with limestone), it reacts with minerals in the stones, sometimes causing them to disintegrate and wash away. Acid deposition can also cause concrete to deteriorate, and it can corrode modern buildings, cars, railroad tracks, airplanes, steel bridges, and pipes above and below ground.

What's Being Done?

Because of these problems and the adverse effects of air pollution has on human health, a number of steps are being taken to reduce sulfur and nitrogen emissions. Most notably, many governments are now requiring energy producers to clean smokestacks with scrubbers that trap pollutants before they are released into the atmosphere and to reduce car emissions with catalytic converters. Additionally, alternative energy sources are gaining more prominence and funding is being put toward the restoration of ecosystems damaged by acid rain worldwide.

Acid rain

Acid rain

 Acid rain is made up of water droplets that are unusually acidic because of atmospheric pollution, most notably the excessive amounts of sulfur and nitrogen released by cars and industrial processes. Acid rain is also called acid deposition because this term includes other forms of acidic precipitation (such as snow).

Acidic deposition occurs in two ways: wet and dry. Wet deposition is any form of precipitation that removes acids from the atmosphere and deposits them on Earth’s surface. Dry deposition polluting particles and gases stick to the ground via dust and smoke in the absence of precipitation. Even though dry, this form of deposition is dangerous as well, because precipitation can eventually wash pollutants into streams, lakes, and rivers.

Acidity itself is determined based on the pH level (the amount of acidity or alkalinity) of the water droplets. The pH scale ranges from 0 to 14, with a lower pH being more acidic, while a high pH is alkaline, and seven is neutral. Normal rainwater is slightly acidic, with a pH range of 5.3-6.0. Acid deposition is anything below that range. It is also important to note that the pH scale is logarithmic, and each whole number on the scale represents a 10-fold change.

Today, acid deposition is present in the northeastern United States, southeastern Canada, and much of Europe, including portions of Sweden, Norway, and Germany. In addition, parts of South Asia (particularly China, Sri Lanka, and southern India) and South Africa are all in danger of being affected by acid deposition in the future.

What Causes Acid Rain?

Acid deposition can be caused by natural sources such as volcanoes, but it is mainly caused by the release of sulfur dioxide and nitrogen oxide during fossil fuel combustion. When these gases are discharged into the atmosphere, they react with the water, oxygen, and other gases already present there to form sulfuric acid, ammonium nitrate, and nitric acid. These acids then disperse over large areas because of wind patterns and fall back to the ground as acid rain or other forms of precipitation.

The gases most responsible for acid deposition are a byproduct of electric power generation and the burning of coal. As such, man-made acid deposition began becoming a significant issue during the Industrial Revolution and was first discovered by a Scottish chemist Robert Angus Smith in 1852. In that year, he discovered the relationship between acid rain and atmospheric pollution in Manchester, England.

Although it was discovered in the 1800s, acid deposition did not gain significant public attention until the 1960s, and the term "acid rain" was coined in 1972. Public attention further increased in the 1970s when the "New York Times" published reports about problems occurring in the Hubbard Brook Experimental Forest in New Hampshire.

Branches of Physics

 

Branches of Physics

The physical universe has many moving parts and is not simply what is observed through the naked eye. Physics is also how the most prominent objects interact with the smallest and everything in between. Since physics is such a broad subject, it has to be broken into smaller categories or disciplines, also known as fields of study.

There are three main categories of modern physical study:

1. Classical physics covers electromagnetism, classical mechanics, thermodynamics, and statistical mechanics. Classic physics provides action and reaction, showing how objects acting in a system will interact with other objects in that same system.
2. Relativity has two types of study; there is general and specific relativity. General relativity deals with how the law of gravity interacts with objects; this has a significant bearing in astrophysics and astronomy. Special relativity concerns how objects interact in a vacuum or are devoid of gravity.
3. Quantum physics is the most recent course of study in physics. Here, scientists study quantum mechanics, quantum statistics, quantum electrodynamics, and quantum field theory. This branch deals primarily with objects at an atomic and subatomic level. It answers questions like, "what makes a proton different from a neutron?"

Mechanics

The study of mechanics is both broad and specific. Broadly, mechanics study objects, their motion, energy, and how they interact with other objects and energy. There are two sub-branches of mechanics, quantum mechanics and classical mechanics.

• Quantum mechanics, studies how atom and subatomic particles act and react with one another; similar to how the atom is held together, what happens if two atoms collide? What makes up the atomic particles; how and why do two atoms bond; what holds together millions of atoms into a complex compound?
• Classical mechanics follows the same principles as quantum, at a much larger scale. Examples of classical mechanics would be predicting planetary orbits or the path of a bullet, black holes, friction between a car tire and the road, why water has surface tension, or the arc of a baseball as it is thrown across home plate.

Mechanics can explain a minor interaction, like why an electron is attracted to a proton, and the most significant interaction, like why the earth orbits the sun.

Optics

One of our two most important senses is that of sight. In physics, the study of light and its properties is called optics.

One reason light is a fascinating study subject is that it contains the properties of a wave and particles. Additionally, electromagnetic waves make up light, meaning it has properties of electricity and magnetism and does not need a medium to move.

There are several different types of light:

• Visible
• Ultraviolet
• Infrared
• X-ray
• Radio Waves
• Gamma Rays

 

Various Branches of Physics

Physics can be classified into various branches, but classical physics is mainly concerned with energy and matter. The traditional branches of classical physics are Optics, Acoustics, Electromagnetics, and Classical mechanics. With the rapid development of physics, the scope of the subject is growing so large that it is not possible to cover physics under the above branches. A number of main branches of physics are discussed below.

Mechanics

Mechanics is the branch of physics that deals with the motion of an object without or with the reference of force. Mechanics can be further divided into two branches, namely quantum mechanics and classical mechanics. Quantum mechanics deals with the behaviour of the smallest particles like neutrons, protons, and electrons, while classical mechanics is the branch that deals with laws of motion of forces and physical objects.

Optics

This branch of physics deals with the behaviour, propagation, and properties of light. Optics can be simply described as the study of the behaviour of infrared light, visible light, and ultraviolet.

Thermodynamics

Thermodynamics deals with the study of heat and its relation with work and energy. Thermodynamics also deals with the transmission of heat energy by means of convection, conduction, and radiation.

Electromagnetism

Electromagnetism deals with the study of electromagnetic force like electric fields, light, magnetic fields, etc. There are two aspects of electromagnetism which are “electricity” and “magnetism”.

Relativity

This branch of physics deals with the theorem that was formulated by Albert Einstein. The theory of relativity states that space and time are relative and all the motion must be relative to a frame of reference.

Acoustic

Acoustics deals with the study of sound and its transmission, production, and effects. Acoustics mainly involves the mechanical waves in gases, liquids, and solids, which include vibration, sound, ultrasound, and infrasound.

What is physics?

                                                             What is physics?

 What Matter Means in Physics

By 

Andrew Zimmerman Jones

Andrew Zimmerman Jones

Math and Physics Expert

• M.S., Mathematics Education, Indiana University
• B.A., Physics, Wabash College

Andrew Zimmerman Jones is a science writer, educator, and researcher. He is the co-author of "String Theory for Dummies."

Learn about our Editorial Process

Updated on May 06, 2019

Matter has many definitions, but the most common is that it is any substance which has mass and occupies space. All physical objects are composed of matter, in the form of atoms, which are in turn composed of protons, neutrons, and electrons.

The idea that matter consisted of building blocks or particles originated with the Greek philosophers Democritus (470-380 BC) and Leucippus (490 BC).

Examples of Matter (and What Isn't Matter)

Matter is built from atoms. The most basic atom, the isotope of hydrogen known as protium, is a single proton. So, although subatomic particles aren't always considered forms of matter by some scientists, you could consider Protium to be the exception. Some people consider electrons and neutrons to also be forms of matter. Otherwise, any substance built of atoms consists of matter. Examples include:

• Atoms (hydrogen, helium, californium, uranium)
• Molecules (water, ozone, nitrogen gas, sucrose)
• Ions (Ca2+, SO42-)
• Polymers and Macromolecules (cellulose, chitin, proteins, DNA)
• Mixtures (oil and water, salt and sand, air)
• Complex Forms (a chair, a planet, a ball)

While protons, neutrons, and electrons are the building blocks of atoms, these particles are themselves based on fermions. Quarks and leptons typically aren't considered forms of matter, although they do fit certain definitions of the term. At most levels, it's simplest to state simply that matter consists of atoms.

Antimatter is still matter, although the particles annihilate ordinary matter when they contact each other. Antimatter exists naturally on Earth, although in extremely small quantities.

Then, there are things that either have no mass or at least have no rest mass. Things that are not matter include:

• Light
• Sound
• Heat
• Thoughts
• Dreams
• Emotions

Photons have no mass, so they are an example of something in physics that is not comprised of matter. They are also not considered "objects" in the traditional sense, as they cannot exist in a stationary state.

Phases of Matter

Matter can exist in various phases: solid, liquid, gas, or plasma. Most substances can transition between these phases based on the amount of heat the material absorbs (or loses). There are additional states or phases of matter, including Bose-Einstein condensates, fermionic condensates, and quark-gluon plasma.

Matter Versus Mass

Note that while matter has mass, and massive objects contain matter, the two terms are not exactly synonymous, at least in physics. Matter is not conserved, while mass is conserved in closed systems. According to the theory of special relativity, matter in a closed system may disappear. Mass, on the other hand, may never have been created nor destroyed, although it can be converted into energy. The sum of mass and energy remains constant in a closed system.

In physics, one way to distinguish between mass and matter is to define matter as a substance consisting of particles that exhibit rest mass. Even so, in physics and chemistry, matter exhibits wave-particle duality, so it has properties of both waves and particles.