Why Jefferson refer to his election to presidency as the "revolution of 1800"?

It is considered to be the revolution of 1800 because for the first time the power is transferred from one party to another.

Explanation:

John Adams who was the successor of George Washington won the presidential elections and during his term the war between many political factions were open and condemned each other on an open forum. This created public dissatisfaction and his term was criticized by many specially by democratic republicans and Thomas Jefferson.

French was continuously searching Us ships and many dangerous confrontations were undertaken by the French against US which made Adams to issue serious punishments on the basis of treason. He punished many people whoever were writing against the Us officials or defaming the US Government. This created contempt on John Adams. After which it was not easy for Jefferson to come in power. He reached the presidency position and being the author of Declaration of Independence, he also followed the ideals of enlightenment.