Depending on the story and the structure, you can just straight up put a time and date on the events (in the chapter title, for example.) That works OK in stories where the characters can be expected to keep time and events in mind. That method is often used when characters in the military are involved and where the writing takes its cues from military "action reports."
A smoother way is to inject some common event into both scenes.
Say scene 2 consists of a couple of characters holding a conversation close to a church in a European city. As that scene ends, the clock in the bell tower of the church strikes 12 - the bonging notes of the clock interrupt the conversation.
Scene 1 picks up as another character a couple of city blocks away hears the church clock strike noon, signalling the beginning of a lunch break from construction work.
Any common event will work, but one related to the story is best. David Drake used this technique in the novel Rolling Hot to tie together a bunch of nearly simultaneous events at the beginning of the novel. There's an explosion heard all across the camp. There are short introduction scenes for several characters in which the sound of the explosion is heard. That one sound synchronizes all the threads.