After the long cutscene, you'll find that Cloud isn't with you anymore. He fell to the gigantic lifestream explosion in the Northern Crater. However, you don't have to worry about Cloud; he'll show back up later.
For some time henceforth, you're mainly controlling Tifa, and Cloud's materia and accessory have been returned to your inventory. Tifa wakes up after being knocked out for seven days. Barret shows her what's happening outside; the Meteor is coming from the skies.
Rufus and Heidegger show up and clap you in irons. They have decided to cheer up the populace with a televised public execution. For a brief while, you're controlling Barret. Follow Tifa and the soldiers downstairs, where you'll see a save point. You'll end up in the press room. Scarlet throws Tifa in the gas chamber and the guards lock her there, but you'll notice a guard drops the key.
Just as Scarlet, the sadistic executioner, starts to see Tifa squirm and beg for mercy, the base gets attacked by one of the Weapons released from the crater. The monster's name is Sapphire Weapon, although the name isn't mentioned anywhere in the game. Also, it turns out one of the reporters was Cait Sith in disguise. Barret can't easily get the gas chamber door open, so Cait Sith suggests opening it from elsewhere, and they join up. Equip the characters as you see fit.
As you leave, you find out that Scarlet woke up and locked the door from inside. Cait Sith gets a great idea, but won't tell you what it is - head right down to the airfield. Outside, if you've gotten Yuffie, she's here - talk to her and she's back in the fray. Press on. Head to the upper level on the airfield and go right where the big airship is waiting.
Meanwhile, in the gas chamber, help Tifa escape confinement. Follow the on-screen instructions to do the following:
- Slide down, and pull the key closer.
- Pick up the key with your feet.
- Take the key with your mouth.
- Transfer the key to your hand to unlock the manacles.
Then use the console on left to shut down the gas. Sapphire Weapon wants to really roast the Junon base, and gashes a big hole in the wall. It's right where the gas chamber was, so to get out climb down the wall and run down the long barrel. Scarlet shows up and tries to slap Tifa. Tifa isn't handcuffed now, of course. You'll enter into a slapping match, and eventually Scarlet yields and notes that Tifa has nowhere to go but to jump down to her death. Luckily, the airship Highwind shows up. Barret tosses down a rope and Tifa leaps aboard, escaping.
Now it's time to get used to the various facilities of the Highwind, find out how all of the stuff there works, and talk to the folks aboard about the plans on what to do next. There's a whole lot of stuff to do at this point. What you can do at this time: train your fellows, explore stuff, and go to some places you couldn't previously.
Gold Saucer is closed: Dio is at the door, saying he's not sure if it pays to keep it running. So you can go catching Chocobos, but you can't race them right now. You also can't go back to Gaea's Cliff and get back to where Sephiroth is sitting, as the guy who takes responsibility of that sledding track won't let you go down the hill.
Also note that Highwind cannot land on forests, mountains or snow. You can reach places like the Round Island (an uncharted island on the top northeast corner of the world map), but you can't land there.
You can now visit two small islands. South of Gongaga and Cosmo Canyon is the Cactus Island; there you can morph Cactuers into Tetra Elemental accessories. In a different sea, north of the Chocobo Farm, is the Goblin Island; there you can learn the Goblin Punch enemy skill and steal Zeio nuts from the Goblins; the nuts will be later necessary to breed a Gold Chocobo.
A lot of people, including Bugenhagen if you visited Cosmo Canyon, will suggest that there's an island to the south with springs of Lifestream. If you happened to open the menu near Temple of the Ancients, you may have wondered what the "Mideel Area" is. It's a town just east of the Temple of the Ancients. Mideel is a nice, small, quiet town, with a cute dog that seems to like Tifa. Looking around you'll find Cloud. Cloud is not being very healthy at this time. Tifa will stay at his side, and automatically gives you back her materia and accessory.
While you're in Mideel, you can visit the shops and buy some really nice gear and fine accessories. Also, there's a small white Chocobo here. Feed him some Samolen Greens, and scratch behind his ears (as advised by Choco Bill said back at the farm), and he'll give you a Contain materia, which is a spell materia that has some unusual properties. If you check the back of the weapon shop, you'll find a locked door. Go outside down the path to the left and the floor should creak. Search to find a rusty key, and try to use it in the lock, only it will break off. Be honest when the man asked you what happened, and you'll get a Curse Ring. You can also go inside one of the houses to find an Elixir, only for once the man inside will complain, just be honest again and you'll get to keep it.