Definition and simple explanation:

Of the spring, sometimes called Lenz, is the season between winter and summer. In the northern hemisphere, the months of March, April and May fall into the meteorological spring, while in the southern hemisphere in the months of September, October and November, the meteorological spring prevails.
At the beginning of spring, nature awakens, both plants and many species from their hibernation. Squirrels, badgers, moles, beavers, brown bears, hedgehogs, groundhogs or bats are beginning to take action. Migratory birds are constantly returning from the warmer areas.
The days become longer in the spring, the nights shorter. The sunlight lets the first buds sprout and soon blossom. Snowdrops and crocuses are usually the first indicators of spring as early flowering plants. Mild temperatures and more sunlight also have a noticeable effect on humans. Sunlight leads to an increased release of serotonin, a neurotransmitter and hormone in our brain or body. Serotonin causes us to feel well.
But spring brings not only positive sides with it. With the spring also the time of the allergy begins. Alder, elm, ash, poplar, willow, birch release pollen already in the spring months) and can cause allergic reactions.