The formation of cis-trans isomers is a consequence of the absence of free rotation. Geometric isomers that only differ from each other in the 3-dimensional arrangement of the substituents in space. They have identical bonding and substituents. Alkane.
What sells out first: Christmas/New Years, Presidents Week in February, Spring Break Week in March, Easter Week and July/August sailings when the children are out of school. To get the space you want on the cruise and necessary air arrangements, don't hesitate to book 9 to 11 months in advance if possible. The remainder of February, March and April sailings usually start to fill up once the weather starts to turn cold in the Northeast and Midwest.
The best time to buy tickets to the Caribbean is 144 days in advance, on average; 318 days in advance for flights to Asia; 262 days for flights to Africa; 251 days for Mexico; 244 days for the South Pacific; 213 days for the Middle East; and 96 days for Central and South America.