Here’s a refined color palette for your calendar application, structured into three groups based on your specifications: dark colors, lighter colors, and medium colors. The palette transitions from dark to light, with yellow as the root of divergence.

 <Calendar Application Palette>
1. Personal - 
                            
                            #2E1A47
                         - Dark Purple 
2. Events - 
                            
                            #FF6F20
                         - Vibrant Orange
3. Exams - 
                            
                            #2F4F4F
                         - Dark Slate Gray
4. Course Schedule - 
                            
                            #1E90FF
                         - Bright Blue
5. Course Events - 
                            
                            #F7C6A0
                         - Pink Sand
6. Band Events - 
                            
                            #A40000
                         - Dark Red

7. Time Blocks - 
                            
                            #00BFFF
                         - Deep Sky Blue
8. Misc Dates - 
                            
                            #708090
                         - Slate Gray
9. Academic Calendar - 
                            
                            #FFD700
                         - Bright Yellow
10. Sleep - 
                            
                            #40E0D0
                         - Turquoise
11. Hokie Sports - 
                            
                            #F5DEB3
                         - Wheat

12. Important - 
                            
                            #FF7F50
                         - Coral
13. Tasks - 
                            
                            #4169E1
                         - Royal Blue
14. Urban Policy - 
                            
                            #FF1493
                         - Deep Pink
15. Sustainable Urb. - 
                            
                            #2E8B57
                         - Sea Green
16. Band - 
                            
                            #C71585
                         - Medium Violet Red
17. Recurring - 
                            
                            #800080
                         - Purple
18. Long-Term - 
                            
                            #A9A9A9
                         - Dark Gray
19. US Holidays - 
                            
                            #D5006D
                         - Fuchsia

Color Palette Description:

• Dark Colors: These provide a strong visual base for the more important calendars (Personal, Events, Exams, etc.).
• Lighter Colors: Bright and inviting, these colors are suitable for blocks that may require less emphasis but are still important (Time Blocks, Misc Dates, Academic Calendar, etc.).
• Medium Colors: These colors balance between the extremes, capturing attention without overpowering (Important, Tasks, Urban Policy, etc.).

Would you like to make any adjustments to specific colors or their placements? Or do you have any other requirements for the design of your calendar application?