As a non-radio enthusiast, I was following along until this sentence.
14080Kc ( = 14080 KHz = 14.08 MHz), 10136 (=10.136 MHz) and 7074 (=7.074 MHz) are the frequencies of the radio channels being used.
The ionosphere (which is partly powered by the sun) tends to dissipate at night and not reflect higher frequencies as well. Thus one tends to use lower frequencies during the evening/night and higher frequencies during the day.
As an aside, an ionosonde is a radar which can measure and display the reflectivity of the ionosphere in real-time as function of things like height/range, radio frequency and direction. Not many people get to play with them, but they are a great tool to learn how the ionosphere works. You can sit in front of the display and watch in real-time as the ionosphere's response changes and it's height increases as night approaches and see how it varies from day to day. Beats reading about it in a text book and it's fascinating to watch.
Here's a link to an online ionosonde, displaying ionograms in real-time, updated every 5 minutes:
The other comment under yours does a great job explaining things too.
As an additional note KC (Kilo Cycles) is the old way of writing Kilohertz. I just happen to prefer writing Kc for some reason even though I know it's no longer "correct"