You can do this both ways. Which way you decide as a group to handle scene aspects will subtly but powerfully change the way your games works. Consider this passage from Fate Core (Electronic Edition, p. 59):
In Fate, aspects do two major things: they tell you what’s important about the game, and they help you decide when to use the mechanics.
and this passage from the next page:
Because aspects tell us what’s important, they also tell us when it’s most appropriate to use the mechanics to deal with a situation, rather than just letting people decide what happens just by describing what they do.
GMs, this comes up for you most often when you’re trying to figure out whether to require a player to roll dice. If a player says, “I climb this ladder and grab the idol,” and there’s nothing special about the ladder or the idol, then there’s no real reason to require an overcome action to grab it. But if the situation aspects tell you that the ladder is a Rotting Rope Ladder and the idol is Protected by the Wrath of the Gods, then you suddenly have an element of pressure and risk that makes it worth going to the dice for.
Got all that?
Okay, so what does that mean?
It means that by using implicit aspects, your group is saying that mundane details are always important. This will make your games bend a bit more toward a simulation-y play style, and de-emphasise all the other aspects (not just scene aspects) that have been explicitly called out.
If you require explicit aspects, your group is saying that the story is tightly scoped to the themes and issues marked by explicit aspects. Look back to that quote about how aspects define what's important about the game, and how they tell the GM when to engage the mechanics. If you've only got explicit aspects, then the players know that the actions they take that don't touch on aspects are going to pretty much just be givens, because success or failure there is not important. The only time you roll, and possibly fail or succeed, is when your actions bring you into direct contact with the defined aspects – those things that your group or GM have marked as being relevant to the story you're playing out.
This difference can deeply affect (and effect!) your game. If your GM says that weather is sunny, that's not really an aspect worthy of mention in the average game, is it? But if you're playing a game about weather-working islander wizards, then making it an aspect – Brilliantly Sunny Weather – marks it as an important, relevant thing that you can all expect will be mechanically relevant when you, say, try to swamp a boat by summoning a sudden squall. Conversely, introducing Brilliantly Sunny Weather into the aforementioned 'average' game is a way the GM can send a message: "This is important or is about to become important. Pay attention to it. Use it to your advantage, or beware of it being used against you." Perhaps a giant falcon is about to dive out of the sun directly at the group!
So use this "switch" to say how tightly your game is going to be focused on the story implied by your Game and Character aspects, and how tightly focused your scenes will be on their explicit Scene aspects. Less desired focus: implied aspects are good! More desired focus: implied aspects are just muddying the waters.
The default setting for this switch in Fate Core is right there in those quoted passages: explicit aspects are the only aspects. This serves the goals of the designers, which is to produce a tight base system that strongly supports creating stories with strong themes and challenges. Fate Core is also deliberately designed to be an easily hackable base system though, and this is one of the easiest ways to change the defaults in order to produce a different play experience.