Spring swings: Why is the weather so changeable?

Temperatures continue to rise and fall in the coming days, with the reason for this lying in the jet stream.

The jet stream is one of the fastest movements of air blowing on earth. It is a strong, tubular ribbon of wind that travels along a near-horizontal axis around five to seven miles above the Earth's surface.

It flows high above us, causing changes in wind and pressure, which affects our weather. Though near-horizontal, it can still buckle and meander, slowing down the movement of pressure systems overhead.

The jet stream exists largely because of temperature contrasts, with cold air on the northern side of the jet stream, and warm air to the south.

When the jet stream sits to our north we tend to see warmer weather imported from the south, and the opposite is true when it sits to our south. When it pushes directly overhead, we tend to receive more unsettled weather from the west.

When there is a greater temperature difference between the equator and poles during winter, the jet stream consequently gets stronger, driving more low pressure systems over.

At present, our jet stream is meandering a lot, which is the primary cause for our changeable weather conditions.