Cloud watching

 Straight line HAARP clouds??

`Straight edges of stratus and altostratus clouds are fairly common and usually indicate a very strong demarcation between air masses, especially at the rear of a receding cold front with very dry air plunging down from the north behind the cold front (and dropping rapidly in altitude, thereby aquelching the lifting of air that produces condensation and clouds).

These kinds of edges can also be seen at the front of an advancing squall line in the summer, but it sounds like what you have observed occurred during winter.

Straight edges within stratus clouds may be an indication of wave motion, which occurs at all levels of the atmosphere and is most easily detected when clouds are present. Wave motion of amazing consistency, width, and duration produces undulating patterns that are beautiful and extensive.

Another physical cause of such edges could be a very long wavelength wave that lifts an expanse of air, resulting in a cloud with a sharp edge in opposite directions; this is more likely for altostratus than for stratus.

Cold/warm fronts may not normally have clear demarcation lines at the leading edge, but can more commonly have such an edge behind the front; this is especially true for cold fronts.`

by Meteorologist David R. Cook:

http://www.newton.dep.anl.gov/askasci/wea00/wea00361.htm