Ireland encountered economic difficulties when it adopted the euro, the currency of

Euro is the currency of the members of European Union.

there are a lot of factors that could cause difficulties when adopting a new currency, such as inflation, mass confusion, market preference, potential fraud, etc

hope this helps

Answerair masses develop near the equator are warm; tropical air mass

Why the planet stays in orbit is because of inertia (object stays in motion until a force changes it’s motion) also the atmosphere and gravity!