The term 'Summer Phenomenon' can be broken down into two crossword solutions: HEAT (4 letters) and HEATWAVE (8 letters). HEAT is a form of energy that is transferred from one object to another due to a difference in temperature. Heatwaves are periods of abnormally high temperatures that last for several days or weeks. They are often accompanied by high humidity, which can make the air feel even hotter. Heatwaves can cause serious health problems, such as HEAT exhaustion and HEAT stroke.