This may be a little too Sci-Fi, so please move it if necessary.

In episode 5 of Gundam 00 (available on YouTube here), the Gundam Exia uses a single sword swing to part the clouds and give the Gundam Dynames a clear shot at a target in orbit.

This is far from the first time I've seen something like this happen in a story, but I was curious: How much force is actually needed to rapidly force clouds to move apart like that?

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Not an armored Jigglypuff

"I salute your genetic superiority, now Get off my planet!!" -- Adam Stiener, 1st Somerset Strikers

I'm interested in it also but for a different reason. In an episode of Smallville, Clark gains the ability to use super breath and manages to part the clouds creating a clearing in a circular pattern. In other words, he made a cloud donut.

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ASVS('97)/SDN('03)

"Peppercorn Tomatoes slathered in broken guacamole sauce. Put it in the microwave and press puree. 5 seconds in the dumpster and it is ready to be cooked in the freezer at -350 degrees for twenty minutes. Apply pressure in various hamster spots and scream like a psychotic banshee." My reply when asked what was on my mind.

By the sacred crotch of Arkvoodle!

Splitting clouds has nothing to do with force, and everything to do with drying out the atmosphere. If you've got convective clouds going, it's plausible there's no amount of force you could apply, as by the time the air you moved got to altitude (cooling all the way), your air would be just as moist as the air your trying to move to cause the clouds to split. IOW, it may be a cool looking effect, but the only way you're actually going to manage it is to heat the cloud up enough to cause the dew point depression to massively increase.

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"preemptive killing of cops might not be such a bad idea from a personal saftey[sic] standpoint..." --Keevan Colton
"There's a word for bias you can't see: Yours." -- William Saletan

So then it becomes a problem of how fast you need to swing your sword in order to friction heat the air to above the local dew point.

Look at the Castle Bravo test. It works - it certainly disrupts the cloud layer. But it just creates more clouds - moisture gets pushed away, concentrating into decks that form, get obliterated, but are already in the process of being obscured by the formation of the next deck. And that was a 15 megaton blast.

What you really need is dry air.

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Give fire to a man, and he will be warm for a day.
Set him on fire, and he will be warm for life.

What about the method used in Smallville?

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ASVS('97)/SDN('03)

"Peppercorn Tomatoes slathered in broken guacamole sauce. Put it in the microwave and press puree. 5 seconds in the dumpster and it is ready to be cooked in the freezer at -350 degrees for twenty minutes. Apply pressure in various hamster spots and scream like a psychotic banshee." My reply when asked what was on my mind.

By the sacred crotch of Arkvoodle!

What's in Superman's lungs is really up to author or at least character design fiat. If he breathes out a lot of hot, dry air, it'll act like any other high-pressure zone, pushing away clouds, etc.

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Give fire to a man, and he will be warm for a day.
Set him on fire, and he will be warm for life.