As an expert in the field of electrical engineering, I can provide a comprehensive explanation regarding the flow of electricity through the air. The ability of electricity to travel through the air is a complex phenomenon that depends on various factors such as atmospheric conditions, humidity, and the presence of contaminants. Let's delve into the details of how and under what conditions electricity can flow through the air.

Electrical Conductivity in Air
Air, under normal conditions, is an excellent insulator. This is because it is composed mostly of nitrogen and oxygen, which are both non-conductive gases. However, there are certain conditions where air can become conductive.

Factors Affecting Air Conductivity

1. Atmospheric Pressure: At higher altitudes, the air is thinner and has fewer particles to carry an electrical charge, which reduces its conductivity.

2. Humidity: Moisture in the air can increase its conductivity. Water molecules can dissociate into ions, which can carry an electrical charge.

3. Contaminants: Dust, smoke, or other particulates can also enhance the conductivity of air by providing a medium for charge carriers.

4. Electrical Field Strength: A strong enough electrical field can ionize the air, creating a conductive path for electricity to flow.

Ionization and Arcing
When the electrical potential difference between two points in the air becomes sufficiently high, the air can become ionized. This ionization process creates free electrons and ions, which can then conduct electricity. This is the principle behind lightning, where a massive electrical discharge occurs due to the ionization of the air.

Ohmic Behavior
The term "ohmic" refers to the linear relationship between voltage and current in a material. As you mentioned, air is not ohmic. This means that the current through the air does not increase linearly with the voltage applied. Instead, there is a threshold voltage, known as the dielectric strength of air, which must be exceeded before the air will conduct electricity.

Dielectric Strength
The dielectric strength of air is the minimum voltage required to cause ionization and breakdown, leading to a conductive path. This value is approximately 3 million volts per meter (3 MV/m) under standard atmospheric conditions.

Corona Discharge
Before the dielectric strength is reached, a phenomenon called corona discharge can occur. This is a type of electrical discharge that takes place when the electric field around a conductor is strong enough to ionize the surrounding air, but not enough to cause a complete breakdown. It is often seen as a faint blue glow around high voltage equipment.

Electrical Breakdown
When the voltage is high enough to overcome the dielectric strength, an electrical breakdown occurs. This results in a conductive path, allowing a large current to flow. This is the point at which an electrical arc can form, which is a visible discharge of electricity through the air.

Applications and Safety Concerns
Understanding the conditions under which electricity can flow through the air is crucial for various applications, including high voltage power transmission, lightning protection, and electrical safety measures. It is also important for designing systems that can prevent or mitigate the effects of electrical discharges.

In conclusion, while air is generally a good insulator, it can become conductive under certain conditions, such as high voltage, increased humidity, or the presence of contaminants. The flow of electricity through the air is not ohmic, and it involves complex processes like ionization and electrical breakdown. The knowledge of these principles is essential for the safe and effective use of electrical energy.

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Still other materials are not ohmic at all. Air is not ohmic at all. This means that there is no linear relationship between the electrical voltage applied to air and the resulting electrical current that travels through it. The behavior of electricity in air is far more complex.Jan 28, 2014read more >>