$(function() {
    var Images = $("#sky div"), Timers = [];

    var makeFly = function (Id, Range, Duration, Direction) {
        return function () {
            var Way1 = {}, Way2 = {};
            Way1[Direction] = '+=' + Range;
            Way2[Direction] = '-=' + Range;
            $('#'+Id).animate(Way1,Duration).animate(Way2,Duration);
        };
    };

    Images.each(function() {
        var Image = $(this),
            Id = Image.attr('id'),
            Range = Image.attr('data-fly-range'),
            Duration = parseInt(Image.attr('data-fly-duration')),
            Direction = Image.attr('data-fly-direction');

        var fly = makeFly(Id, Range, Duration, Direction);

        Timers[Id] = setInterval(fly, Duration*2);
        fly();
    });
});