Popular wisdom says that you can forecast the weather in the next few hours simply by observing the flight of swallows. If they fly at low altitude, the day is unpleasant and, if they fly at high altitude, it will be sunny.
In reality, the true meteorological indicators are not these birds that Bécquer immortalized in his poem, but insects , especially mosquitoes, that hunt on the fly. When bad weather approaches, mosquitoes avoid the upper layers of the atmosphere, since the prevailing strong winds can knock them down. However, on sunny days , the air currents are notably softer, a circumstance that these and other insects instinctively take advantage of to fly higher , since that is where they are most likely to find a mate ready to mate. Anglo-Saxons know this behavior as hilltopping , which means to rise.
