The 11-meter CB band is usually a local communication band, but when ionospheric conditions align, signals can travel over surprising distances.
Solar activity is one ingredient
The solar cycle affects ionization in the upper atmosphere, changing how certain HF radio signals propagate. Time of day, season, location and geomagnetic activity also matter.
Why skip fades in and out
Propagation paths are dynamic. You might hear several distant stations for a few minutes, then experience a quiet band again. That variation is normal and part of the hobby.
How to observe
Keep a simple log of what you hear and when. Compare your notes with official space-weather information, but remember that a solar index alone cannot predict a specific two-way CB contact.
Read CB skip and DX explained or make a DX log.