In the Episcopal Church, we observe Ember Days four times a year primarily by offering prayers for the ministry. Those who are preparing for Holy Orders in this Church customarily write "Ember Day Letters" to their bishops.
The name for the observance may come from the Anglo-Saxon ymb-ren - a circuit or revolution; something that recurs. Or, it may come from the German quatember, a corruption of the Latin quatuor tempora - "Four Times."
The observances are always on the Wednesday, Friday, and Saturday of the weeks following St. Lucy's Day (December 13), The First Sunday in Lent, Pentecost, and Holy Cross Day (September 14). These times are almost equidistant in the circuit of the year. Prior to Christianity, they appear to have originally been times of prayer and fasting originally related to the agricultural cycle. Some believed that the weather on each of the three days predicted the weather in each of the following three months. Excellent articles about Ember Days may be found on Episcopal Cafe and Wikipedia.
In any event, we are invited to pray at this time for those to be ordained, for the choice of fit persons for the ministry, and for all Christians in their vocation. The prayers which follow are from The Book of Common Prayer and are especially appropriate for use on Ember Days.
I. For those to be ordained
Almighty God, the giver of all good gifts, in your divine providence you have appointed various orders in your Church: Give your grace, we humbly pray, to all who are [now] called to any office and ministry for your people; and so fill them with the truth of your doctrine and clothe them with holiness of life, that they may faithfully serve before you, to the glory of your great Name and for the benefit of your holy Church; through Jesus Christ our Lord, who lives and reigns with you, in the unity of the Holy Spirit, one God, now and for ever. Amen.
II. For the choice of fit persons for the ministry
O God, you led your holy apostles to ordain ministers in every place: Grant that your Church, under the guidance of the Holy Spirit, may choose suitable persons for the ministry of Word and Sacrament, and may uphold them in their work for the extension of your kingdom; through him who is the Shepherd and Bishop of our souls, Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever. Amen.
III. For all Christians in their vocation
Almighty and everlasting God, by whose Spirit the whole body of your faithful people is governed and sanctified: Receive our supplications and prayers, which we offer before you for all members of your holy Church, that in their vocation and ministry they may truly and devoutly serve you; through our Lord and Savior Jesus Christ, who lives and reigns with you, in the unity of the Holy Spirit, one God, now and for ever. Amen.