Climate factor latitude

These five cities Oslo, Rome, Bilma, Kinshasa and Cape Town (see picture) experience fundamentally different climatic conditions due to their differing geographical latitudes. In the northern hemisphere the sun travels across the southern part of the sky from east to west, and in the southern hemisphere it travels across the northern part of the sky from east to west (column 1). The different latitudes of each location mean that their maximum sun heights and day lengths vary significantly throughout the year. 

In Oslo, the climate changes significantly with the season. Oslo has a maximum of almost 19 hours of daylight in summer and about five hours in winter. In summer, the height of the sun varies between 5° and 55°. The closer a location is located to the equator, the less difference there is between the seasons. In Kinshasa, for instance (directly on the equator), day lengths do not vary by more than one hour and the height of the sun varies by only 10°. 

The shallow angle of incidence in equatorial locations optimises the yield of solar energy. Orientation plays a secondary role. The further one moves towards the North Pole, the more an increasingly steep angle of south orientation becomes optimal, and the same is true of a northern alignment in the southern hemisphere (section 2). 

The level of global and direct radiation is highest in the tropics due to the low levels of cloud cover. At the equator, the precipitation levels can clearly be seen from the level of diffuse radiation and the gaps in the direct radiation. The fact that the sun is at its zenith in Kinshasa in winter is shown by the highest radiation values occurring at this time of year (section 3). 

The radiation level also determines the temperature and humidity conditions at any given location. Temperatures rise as one approaches the tropics. The equator with its high precipitation levels and cloud cover does not achieve the same maximum values as the dry deserts, while its annual temperature variation is lowest (section 5). The difference between day and night temperatures is also largest in the deserts because of the high radiation during the day and at night due to lack of cloud cover (section 4). 

In Oslo the need is for heat and humidity whereas in Bilma the need is for coolness and humidity (with night ventilation as one option). In Kinshasa, the need is for coolness and a lack of humidity. The location with the optimal climate is Cape Town, followed by Rome. 

Wind direction and strength depend on geographical position and proximity to seas and mountains. This means that detailed observation is required. 

Climate and latitude