Midday or the time at which the Sun is highest in the sky and therefore offers the lowest angle of incidence between itself and a freestanding object.
Shadows become shorter only during the morning (before noon). Shadows are longest at sunrise and sunset, when the angle with the surface is greatest.
Shadows get shorter as the sun get higher up in the sky and as the sun goes down shadows will get longer so shadows get shorter in the morning and get longer in the afternoon. Also, as the year progresses, the sun's angle in the sky at the same point in each day changes, due to the 23.5 degree tilt of the Earth's axis. In the northern hemisphere, for instance, shadows get longer and longer (again, at the same time of day) until the winter solstice around December 21st, then they start getting shorter and shorter.
When the sun is low at dawn, and low in the evening, the shadows are long. In the middle of the day, when the sun is higher, the shadows are shorter.
mid night
The time when shadows get shorter in the day if from 12 0'clock. Before and after noon the shadows are usually very long.
winter
If you place yourself on the equator at a the time of an equinox, then at mid day your shadow falls directly under your feet because the Sun is directly above you. As the Sun rises to this position and set form it, you shadow will fall to one side of you and the length of this shadow will depend on the height of the Sun in the sky, the shorter it is the higher the sun will be. Thus from the length and position of your shadow you can tell what time it is. Long shadows happen in the morning or evening and short shadows happen towards mid day.
Its because of where the sun is tipped.
The shadows in the Northern Hemisphere are generally longer in the winter than in the summer. Therefore in the summer the shadows are shorter because the sun is more vertical.
summer shadows are shortest and winter shadows are long.
Because the lights that cause them are relatively low. Lower lights ==> longer shadows. Higher lights ==> shorter shadows.
For vertical objects, shadows are shortest when the Sun (or other light source) is directly overhead. This is when taller objects have their shadows under or near them. For horizontal objects, the shadow is shortest when its longest cross section is parallel to the beam from the light source.