On a hard drive, there is an area dedicated specifically to temporary storage called scratch space. This volume space is commonly used with graphic design (like Adobe Photoshop) programs as an overflow when there is insufficient RAM. The data on a scratch disk can be erased dynamically or on a periodic basis. In the picture is an example of the Scratch Disks setup in Adobe Photoshop found under Edit, Preferences, and Performance.
Tip: Setting up an empty partition on your primary hard drive or another drive ensures adequate scratch space.