What causes a squall line?

Related questions

1. Is a tornado a tornado if it doesn't touch the ground?
2. Can thunder kill you?
3. Why is thunder loud?
4. What is the difference between a funnel cloud and a tornado?
5. Can a thunderstorm cause a tornado?
6. What stops a tornado?
7. What is a QLCS tornado?
8. Can Tornadoes be invisible?
9. Why is thundersnow dangerous?
10. How long do snow squalls last?

Tags

1. #ahead
2. #occurs
3. #arranged
4. #system
5. #lifting
6. #formed
7. #squall
8. #front
9. #combined
10. #convection
11. #causes
12. #often
13. #thunderstorms
14. #unusually
15. #become
16. #banded
17. #shear
18. #widespread
19. #where
20. #atmosphere
21. #lower
22. #structure