Some Natural Phenomena
In this chapter we shall discuss two destructive natural phenomena. These are lightning and earthquakes. We shall also discuss what steps we can take to
minimise destruction caused by these phenomena.
LIGHTNING:
lightning is a natural electrical discharge during thunderstorms. It is caused by the buildup of electrical energy in the atmosphere, leading to a sudden release in the form of a visible flash of light.In the 18th century, scientists such as Benjamin Franklin conducted experiments that contributed to the understanding of lightning's electrical nature. Franklin famously conducted his kite experiment in 1752, which helped demonstrate the connection between lightning and electricity.
Formation: Lightning is a sudden electrostatic discharge that occurs during a thunderstorm. It is caused by the separation of positive and negative charges within a cloud and between the cloud and the ground.
Thunderstorms: Lightning is most commonly associated with thunderstorms. The rapid updrafts and downdrafts within a thundercloud create conditions for the development of electrical charges.
Types of Lightning:
Cloud-to-Ground (CG): This is the most well-known type of lightning, where a discharge occurs between a thundercloud and the Earth's surface.
Cloud-to-Cloud (CC): Lightning that occurs between different regions of a thundercloud.
Intra-Cloud (IC): Lightning that occurs within a single thundercloud but doesn't reach the ground
Thunder: Lightning is always accompanied by thunder. The intense heat from a lightning bolt causes the air to rapidly expand and create a shock wave, resulting in the sound we hear as thunder.
Color and Temperature: Lightning can appear in various colors, including white, blue, and even red. The color is influenced by the composition of the atmosphere and the temperature of the lightning bolt. Lightning is extremely hot, with temperatures reaching around 30,000 kelvins (53,540 degrees Fahrenheit or 29,727 degrees Celsius).
Frequency: Lightning is a common natural occurrence, and it is estimated that there are about 8 million lightning strikes per day worldwide.
Safety: Lightning poses a significant risk to people, and safety precautions are necessary during thunderstorms. Seeking shelter indoors and avoiding open areas are crucial safety measures.
the process of lightning formation involves several stages. Here's a detailed explanation of how lightning is formed:
1. Thunderstorm Formation:
Lightning is most commonly associated with thunderstorms, which are large, towering clouds known as cumulonimbus clouds. These clouds form when warm, moist air rises and cools, causing water vapor to condense into water droplets.
2. Charge Separation:
Within a thundercloud, there is a vertical separation of charges. Updrafts within the cloud carry small ice crystals upward, while larger water droplets fall due to gravity. This process creates areas of positive and negative charges within the cloud.
3. Electrostatic Discharge:
As the charge separation increases, an electric field is created between the positively and negatively charged regions within the cloud. When this electric field becomes strong enough, it ionizes the air and creates a conductive path for the electrical discharge.
4. Leader Formation:
A stepped leader is formed, which is a channel of ionized air that extends downward from the cloud towards the ground. This leader is invisible to the human eye and can travel at speeds of about 220,000 miles per hour (354,000 kilometers per hour).
5. Streamers from the Ground:
Simultaneously, streamers of positive charge rise from objects on the ground, such as trees, buildings, or even people. These streamers extend toward the descending stepped leader.
6. Connection and Return Stroke:
When the descending stepped leader and the rising streamer connect, a completed conductive path is formed. This results in the main lightning discharge, known as the return stroke, which travels back up the ionized channel to the cloud. The return stroke is the visible flash that we see as lightning.
7. Afterglow and Thunder:
The rapid heating of the air along the lightning channel causes it to expand quickly. The resulting shock wave produces the sound we hear as thunder. The afterglow, or fading glow, of the lightning channel is also visible for a brief moment after the main flash.
8. Multiple Strokes and Forking:
Lightning strikes can involve multiple strokes following the same ionized channel, and the branching or forking of the lightning bolt can create complex patterns in the sky.