Final answer:
Cold occlusions occur mostly during autumn and winter in Europe and can lead to extreme weather phenomena. Historical periods like the Maunder Minimum during the Little Ice Age highlight times of exceptionally cold temperatures affecting society and agriculture significantly.
Step-by-step explanation:
Cold occlusions most frequently occur in Europe during autumn and winter, although they can happen in other seasons due to the continent's varied climate. The term 'cold occlusion' refers to a stage in the life cycle of an extratropical cyclone when a cold front overtakes a warm front, resulting in the lifting of the warm air at the boundary aloft. Instances of particularly cold weather, such as during the Maunder Minimum, are notable in European history. This period coincided with the Little Ice Age, a time of exceptionally low temperatures in Europe. During the 17th century, events like the Thames freezing, ice forming in the English Channel, and agricultural hardships due to short growing seasons, were evidence of cold conditions.
Although cold occlusions can occur at various times, certain historical periods like the Maunder Minimum or the colder, wetter years starting in 1314, including what's known as the Great Famine of 1315-1317, demonstrate extreme instances when temperatures were low enough to significantly impact European society, agriculture, and the broader climate. These cold spells can lead to a range of weather phenomena, such as heavy snowfall, ice, and frigid temperatures that can disrupt normal life and agriculture.