Out of a clear sky, a few fluffy clouds form. Some of them grow taller, heavier, darker. An anvil top builds ominously. Thunder rolls; lightning flashes; rain falls in torrents.

Day after day, the meteorologist’s weather maps show bands of thunderstorms hanging over the higher mountainous regions east of us.

Scientifically, there’s good reason for the location of these storms.

Water is a remarkable substance. We know it in three forms — solid, liquid, and gas. It takes one calorie to raise the temperature of a gram of water by one degree Celsius.

To lower the temperature of that water by one degree, you have to take a calorie of heat out of it. Basically, that’s the definition of a calorie.

But to change each gram of liquid water into water vapour — into a gas, in other words — requires 540 calories. Conversely, converting a gas into a liquid releases 540 calories.

Are you still with me?

So when wind patterns sweep warm moist air off the Pacific up against the mountain ramparts along the western edges of the North American continent, the mountains force that air to rise. And to cool. Until the water vapour condenses into water droplets.

Boom! Suddenly, 540 calories per gram turned loose in the upper atmosphere!

The sudden explosion of heat — it’s hard to call it anything but an explosion — sends air currents rocketing upwards. Massive anvil-shaped clouds tower up to 40,000 feet (13,000 m, to be consistent in my measurements) into the icy stratosphere.

Turbulent currents boil and swirl. Updrafts rip past downdrafts, like escalators run amok. The internal friction literally tears electrons off molecules of water. Huge electrical imbalances build up.

Until — ka-blam, a bolt of lightning momentarily equalizes the differences.

That’s why thunderstorms tend to form over the mountain chains of British Columbia — particularly the Rockies.

And why thunderstorms have long hung around the summit of Mount Olympus, at 2,918 metres (9,573 ft.) the highest mountain in Greece.

Little wonder that the ancient Greeks, who knew little of the science of thunder and lightning, identified Olympus with the home of the gods. Little wonder, too, that their primary god, the mighty father of all other gods, was Zeus, the god of sky and thunder. Statues of Zeus show him brandishing thunderbolts in his right hand.

I sometimes wonder how much of Zeus’s personality got siphoned over into the biblical Yahweh/Jehovah. Exodus notes that God spoke to Moses in thunder, from the top of a mountain shrouded in black cloud.

Some psalms describe God living in thunderstorms, of striking with thunderbolts. Even the relatively recent Battle Hymn of the Republic sings, “He has loosed the fateful lightning of his terrible swift sword.”

When the prophet Elijah fled up a mountain, he expected to hear God in storm, earthquake, or fire. But he didn’t. Instead, God came in a moment of utter silence. And in the silence, a voice whispered to Elijah.

I suspect this story was recorded as a turning point, between Olympian gods of raw power and ruthlessness, and the beginnings of a God of forgiving love.