Parashat Vaera describes the first seven of the Ten Plagues. This week we’re going to zoom in to the last plague in the Parasha, the plague of hail. When Moshe briefs Pharaoh before the plague he is very clear as to what is going to happen [Shemot 9:18]: “[Hashem is] going to rain down at this time tomorrow a very heavy hail, the likes of which has never been in Egypt from the day it was founded until now”. Moshe promises the biggest and baddest hailstorm of all time, and the hailstones would be wreaking inconceivable havoc.
Except that it’s not just hail. Somewhere along the line, Hashem decides to add some fire to the mix [Shemot 9:23]: “Hashem gave forth thunder and hail and fire came down to the earth, and Hashem rained down hail upon the land of Egypt”. While the fire seems to first come down by itself, it eventually becomes part of the hail [Shemot 9:24]: “There was hail, and fire flaming within the hail, very heavy”. Rashi, quoting from the Midrash Tanchuma, notes that “[This was] a miracle within a miracle. The fire and hail intermingled. Although hail is water, to perform the will of their Maker they made peace between themselves [that the hail did not extinguish the fire nor did the fire melt the hail]”.
What bothers me is not the appearance of fire – it is its disappearance. How would the fire-hail stones be expected to “impact” the Egyptians? Well, a hailstone, assuming it was large enough, would make a big dent, crushing pretty much everything that stood in its way. When a hailstone hit the ground it would release its flammable contents, burning everything in the vicinity. The problem is that the Torah does not record anything in Egypt being burnt. Here is what did happen [Shemot 9:25-34]:
“The hail struck throughout the entire land of Egypt, all that was in the field… the hail struck all the vegetation of the field, and it broke all the trees of the field… Pharaoh sent and summoned Moshe and Aharon and told them… “Pray to Hashem, and let it be enough of His thunder and hail…” the flax and the barley were broken… The wheat and the spelt were not broken because they ripen late… The thunder and the hail ceased, and rain did not come down to earth… Pharaoh saw that the rain, the hail, and the thunder had ceased; so he continued to sin”
Notice all the words that are emphasized that describe the effects of the hail. None of them say “scorched”, “burnt”, or even “lightly toasted”. Where did the fire go?
While I am a rocket scientist, and probably because I am a rocket scientist, I am very hesitant to explain verses of the Torah according to modern science. I’d hate to have my explanation thrown into the waste bin years from now because of some scientific discovery. But Rav Samson Rafael Hirsch started it. In his explanation of the words “Hashem gave forth thunder and hail, and fire came down to the earth”, Rav Hirsch notes that “hailstorms, and for that matter, any other kind of rainstorm, is usually accompanied by the discharge of electricity.” The “fire” mentioned in the Torah is the lightning that preceded the hailstorm. Well, if Rav Hirsch can talk about storms, electricity, and lightning, then I suggest that it’s time we take a quick look at how hail is formed.
Hail requires a “perfect storm”. It begins with a thunderstorm and huge cumulonimbus clouds that bring the rain. The upper levels of the clouds must be below freezing and the storm must have strong vertical winds. Dust particles enter the storm and supercooled water present in the clouds freezes upon contact on the particle, forming an embryonic hailstone. The wind blows the hailstone around the cloud where it picks up more supercooled water, and as a result, it gets larger. Eventually the hailstone either gets blown out of the cloud or it becomes too heavy for the wind to carry, and it falls to the earth.
How fast does a hailstone travel when it impacts the ground? The physics required to answer this question are a little tricky, but if we disregard minor forces such as viscosity of the air, tumbling of the hailstone, and inter-hailstone interactions, we essentially have the force of gravity pulling the hailstone downwards while air resistance tries to slow it down. When the two forces equal each other the hailstone reaches what is called “terminal velocity”. It turns out that the bigger the hailstone, the greater its terminal velocity. Let’s plug in some numbers. The biggest hailstone recorded to date was about 200 mm in diameter. Let’s assume that the hailstones in Egypt were five times bigger. Using the formula below, it can be shown that a hailstone with a diameter of one meter will impact the earth at a velocity of about 350 meters per second. This speed is greater than the speed of sound, and so each hailstone will be accompanied by a sonic boom. Each hailstone will impact the ground with about 6500 kJ of energy, equivalent to about eight hand grenades.
The upshot of these calculations is that we can understand the plague of hail nearly literally as written in the Torah: The plague was preceded by a storm of immense proportions. There was thunder and there was lightning: “Fire came down to the earth”. Then the hail began to fall. Each hailstone was accompanied by a deafening sonic boom. Each hailstone impacted the ground with a mighty explosion of fire and heat, like exploding grenades. To the casual observer, a hailstone would burst open and fire would pour out. The fire was indeed “flaming within the hail”. It was clear that most of the damage was being done by the impact of the hailstones, and so this is what the Torah emphasizes. And because the “thunder” was the combined sound of storm, the supersonic hailstone, and the ensuing explosion, Pharaoh asks Moshe to stop the “hail and the thunder”.
We can use this understanding of the mechanism of the plague of hail in order to understand Pharaoh’s unusual response. In previous plagues Pharaoh had called for Moshe and offered him a bargain: you stop the plague and I’ll give you some kind of carrot. But with the plague of hail, Pharaoh is deeply affected. He calls Moshe and he tells him [Shemot 9:27] “I have sinned this time! Hashem is the righteous One, and I and my people are the guilty ones”. What is the cause of Pharaoh’s epiphany?
I suggest that Pharaoh is shocked to his core by the fire and the water. As Rashi says, fire and water are opposites. The two cannot simultaneously exist: either the fire boils the water or the water extinguishes the fire. In Pharaoh’s world, the Egyptians were fire and the Jewish slaves were water. Rav J.B. Soloveichik, writing in “Festival of Freedom”, explains that the Egyptians were a modern people, living on the cutting edge of technology and culture. They harnessed the power of the Nile to turn their arid land to green. They were cosmopolitan. And of course they were a world power – the only world power. The Jews, on the other hand, were the complete opposite. They were relics from another age. They were shepherds. They lived in their own ghetto in Goshen. The Egyptians tried to integrate the Jews into their society, encouraging them to engage in [Shemot 1:14] “the work of the field”. But the Jews remained separate. In Pharaoh’s world there was no room for both the Egyptians and the Jews, so the Jews would have to make way. The plague of hail demonstrated that fire and water can live together and even feed off each other: fire bred water which, in turn, bred more fire. When Pharaoh sees this, he can begin to understand that somehow, some way, there is room in the world for both Am Yisrael and the Egyptians. He is not ready to release them, but the seeds for their release have been sown.
The future utopian world contains Jews and non-Jews, fire and water, each worshipping Hashem in his own way, each bettering the world, and in the words of Rabbi Jonathan Sacks, each recognizing the “dignity of difference”. While the way in which this will transpire is still unclear, accepting the possibility is a good first step.
Ari Sacher, Moreshet, 5776
Please daven for a Refu’a Shelema for Moshe Dov ben Malka, Yechiel ben Shprintza, Shaul Chaim ben Tziviya, and Yoav ben Chaya.
 The terminal velocity can be approximated by , where d is the diameter of the hailstone in mm, and the velocity is given in meters per second.