Trinity
Trinity Sunday is the Sunday following Pentecost and gives its name to the long series of Sundays following till the end of the Christian Year. They are really what in the Roman Church are called the 'Ordinary' Sundays.
They mark the weekly remembrance and celebration of the Lord's life, death and resurrection - it is strictly speaking not a season, and it is not ordinary either, at least in any pejorative sense. Interspersed throughout the whole of the year are special days for the commemoration of the Blessed Virgin Mary, the Apostles and Evangelists and other saints. along with events during the life of the Lord, e.g. the Transfiguration. There are also Ember Days, days of prayer and fasting especially for the ministry of the Church, and Rogation Days, which along with the Harvest Festival, are connected with the harvest. Wednesday's and Fridays of each week are designated as days of fasting and abstinence. and the Sunday of each week is always a feast day.