To unlock the Cloud Atlas lockbox in Indiana Jones and the Great Circle, follow these detailed steps:

### Step 1: Locate the Weather Station
1. Find the Weather Station: Head to the west of the Sphinx Excavation Site in Gizeh. Follow the large metal pipe to locate the Weather Station. Approach carefully as there are Nazi soldiers standing guard.

### Step 2: Eliminate the Nazi Commander
2. Eliminate the Nazi Commander: Crouch and sneak towards the station, grabbing an improvised weapon on the way. Take out the Nazi Commander first, as he has a whistle that can be used to call for reinforcements.

3. Hide the Bodies: Make sure to hide the bodies of the soldiers you eliminate to prevent any search parties from investigating.

### Step 3: Access the Locked Chest
4. Access the Locked Chest: Once the soldiers have been dealt with, proceed into the Weather Station and find the locked chest. This will initiate the Cloud Atlas Mystery.

### Step 4: Gather Clues
5. Gather Clues: Head into the room opposite the chest and look for documents titled ‘Cloud Atlas Page’ and ‘Cloud Status Logbook’.

### Step 5: Solve the Cloud Atlas Puzzle
6. Solve the Cloud Atlas Puzzle:
– Cloud Atlas Page: This page lists different cloud classifications with numbered pictures.
– Cloud Status Logbook: This logbook lists different cloud types recorded at different times of the day.

7. Translate Cloud Types to Numbers:
– The times written at the bottom of the Cloud Atlas Page are:
– 13.10
– 09.10
– 16.10
– 14.10
– Reference these times in the Cloud Status Logbook to determine the correct clouds:
– 13.10: Cirrus (0)
– 09.10: Stratus (6)
– 16.10: Cirrus (0)
– 14.10: Cumulonimbus (9).

8. Determine the Code:
– The correct code to unlock the chest is 0609, derived from the cloud classifications corresponding to the given times.

### Step 6: Unlock the Lockbox
9. Unlock the Lockbox:
– Return to the chest and input the number 0609 into the lock.
– The chest will open, revealing ₤50 and a Gizeh Medicine exploration guidebook, which will mark every medicine bottle in the Gizeh chapter.

By following these steps, you will be able to unlock the Cloud Atlas lockbox in Indiana Jones and the Great Circle.