In the British Isles

1. On the 23rd of October, in the British Isles a mid latitude depression formed. This would have been in mid autumn which means that the temperatures would have been relatively warmer than in the winter months. Depressions form primarily with two converging air masses, such as the Polar maritime and the Tropical maritime air masses in the UK. Here, Ireland would be exhibiting cold temperatures and most of mainland Britain would have warmer temperatures as it is in the warm sector. Clouds in the warm sector would have most likely been stratus form clouds as opposed to towering cumulonimbus clouds in the colder sector. As these meet the Dry Adiabatic Lapse Rate exceeds the Environmental Lapse rate. The warm air mass is vertically displaced by the colder and denser air mass resulting in the warm air mass rising and thus low pressure. The warm air mass eventually rises until it reaches the dew point, whereby the latent heat of the water causes condensation and precipitation. At a low pressure of 992 millibars, a thick cloud layer would form alongside high levels of precipitation associated with frontal rain. This cloud layer would also act as an insulator, preventing thermal radiation from escaping, meaning that the UK would have relatively mild temperatures with a low diurnal temperature range. As the cold air mass advances the pressure differences, winds and the coriolis effect will cause the cold front to move in a circular direction anticlockwise, until it meets the rear end of the warm air mass. Friction with land also slows down wind entering incoming wind into the low pressure system causing the wind to flow ageostrophically, toward its center. This second convergence will cause a second round of frontal rain, hail and storms as the last of the warm air mass, adiabatically cools and condenses forming an occluded front. This rain would have most likely occurred over northern England where the masses seem likely to meet. Temperatures would generally be around 5-10 degrees celsius at this time of year in the UK. Wind speeds can reach up to 5-7 on the Beaufort scale in depressions in the British Isles. Here the tightly packed Isobars show that there would be high wind speeds as the pressure gradient is very steep over most of the British Isles. In Ireland, due to it being outside of the depression in the cold sector there would have been very low cloud cover of about 1 okta. There would have also been low wind speeds here. In the warm sector cloud cover can reach up to 8 oktas. The depression would focus over north Scotland.

2. Anticyclones can be vast high pressure systems that reside over the UK, often around 1000-3000km wide, which can result in long lasting periods of weather associated with anticyclones. Anticyclones occur when air converges in the troposphere and descends when the Dry Adiabatic Lapse Rate is less than the Environmental Lapse rate. The subsiding air compresses as it descends causing adiabatic warming. The eventually