The Taal volcano in the Philippines suddenly erupted, so how did lightning form?

65438+1October 12, the Taal volcano in the Philippines suddenly erupted. Volcanic ash soared as high as 10- 15 km, and even spread to Quezon city, 72 km away, causing an earthquake and tsunami. We marveled at the spectacular sight and destructive power of volcanic eruption. I believe everyone can see the magical lightning phenomenon from photos and videos, which is much more spectacular than the atmospheric discharge we see. Let's talk about the physical principle of volcanic lightning first. How did it happen?

One of the most common natural phenomena in our atmosphere is lightning. About100,000,000,000,000,000,000,000,000,000,000,000,000 electrons are exchanged between clouds or the surface of the earth. First of all, how does atmospheric discharge happen? Every atom in the universe, including atoms in the atmosphere, is composed of a positively charged nucleus and a large number of negatively charged electrons. Although we usually think that atoms are neutral and the number of electrons in the nucleus is equal to the number of protons, there are some exceptions.

Because some atoms are happy to be ionized, they either gain an electron or lose one (or two, or three) electrons. Just like the sodium atom in the picture above, it is willing to kick out the outermost electrons and become positively charged sodium ions, while the chlorine atom always feels that it is missing an electron and hopes to become chloride ions by gaining an electron. Now, if we separate these charged particles from each other, there will be charge separation, which will produce voltage. When the voltage (also called potential difference) between the two areas becomes large enough, even if there is only air between them, the air will spontaneously conduct electricity and exchange charges quickly, so we see lightning! Lightning basically occurs at high altitude, which is generally a discharge phenomenon between clouds or between clouds and the ground. However, volcanic eruptions often produce lightning! The picture below shows the lightning during the eruption of Eyjafjallajokull volcano in Iceland.

There are some amazing photos of volcanic lightning below, all of which are real shots. The picture below is a photo of the eruption of Eyjafjallajokull volcano in Iceland, taken by helicopter!

Up and down, lightning during volcanic eruption is no less than any atmospheric discharge.

Historically, it is very difficult to catch lightning at close range in volcanic activity. For example, Mount Chaiding in Chile erupted in 2008, which was the first eruption in 9,000 years.

Sakurajima, Japan is a very active volcano in modern history, and it has been erupting almost all the time since 1955. A volcano observatory was established in 1960, and its activities were continuously monitored. Volcanic lightning was observed many times, including this eruption in 1988.

In fact, as early as 1944, when Vesuvius erupted, volcanic lightning was photographed! As shown below:

So how did volcanic lightning happen? To tell the truth, scientists believe that volcanic lightning is the same as normal thunderstorm lightning, but some details cannot be determined by 100%, which is still a research field. But there is a general concept that can explain why this happens when a volcano erupts.

(Step 1) In most cases, atoms are neutral at first, but due to the existence of a lot of free energy, these energies will knock out some electrons loosely attached to atoms, that is, ionize some atoms that originally wanted to lose electrons, and at the same time, those atoms eager to get these newly released electrons can quickly capture these free electrons. (Step 2).

The above two steps are absolutely no problem: because this is a volcano!

When the temperature is about 1500k, there must be enough energy to kick electrons out of some of the loosest atoms, and then these electrons are easily absorbed by other atoms, producing a large number of positive ions and negative ions.

Now, the key step, which is also controversial at present, is to separate the positive charge from the negative charge with positive and negative particles (step 3). Moreover, enough particles must be separated to generate enough potential difference within a certain distance, thus causing discharge! (Step 4). If we can separate the charges, we can theoretically make volcanic lightning. So how do we distinguish these charges? At present, a large number of ionized atoms, including positive ions and negative ions, are in a chaotic environment at high temperature. These atoms are all erupting from the depths of the earth, which contains many rich elements.

These elements have different masses and different radii! When they are erupted by volcanoes, the temperature will gradually decrease as time goes by. This is very important for the speed of the atom/ion in question.

Generally speaking, when atoms and ions explode, they move very fast at first, but as time goes on, they will cool down and slow down. There are two very important factors that make it easy to distinguish between positive and negative charges. First of all, the masses of these ions are far from each other! The heavier the atomic weight of an element, the slower it moves, even if it is at the same temperature as a lighter element! This also means that heavier ions have greater inertia and it is more difficult to change their momentum. So these slow-moving heavy ions and fast-moving light ions move in very different ways. This is true at any temperature!

The second very important factor: what distinguishes these positive and negative ion types? Positive ions and negative ions are quite different in size and cross section.

Generally speaking, the negative ion cross section is large and the positive ion cross section is small! Why is this? Because more electrons are put on atoms, they will repel each other; If the atom is neutral, the volume of the atom will increase, and the nucleus (there are fewer protons than electrons in the ion) will not be able to catch electrons. On the other hand, in order to become a positive ion, the atom kicks the electron out of the atom, and the nucleus (with more protons in the ion) can catch the electron more tightly than before! This means that the cross section of negative ions is larger than that of positive ions, so their interaction is very different from that of positive ions!