What are April showers and where do they come from?

April showers are a very British weather phenomena - localised torrential downpours that seem to appear out of nowhere just in time to ruin a sunny spring day. But where exactly do these spontaneous downpours come from? The main cause is a contrast in air temperature at different heights that is particularly distinct in April. The temperature of the air in April is still cool following Winter but the ground has begun to warm up as it is heated by the Spring sunshine - which can be as strong as in late Summer. As the sun heats the ground it sets off rising currents of air. This happens because the air near the ground, warmed by the land is more buoyant than the cold air above it. This leads to more unstable air, which rises rapidly forming clouds and showers. Whilst this happens throughout the year, it is more dramatic in April due to the vertical difference in temperature.