The climate of a place is dependent upon the following factors:
3. Proximity to Sea.
4. Proximity to Hills.
5. Prevailing wind direction.
6. Prevailing ocean current
Now I will explain the above factors in a little more detail.
Latitude is the most important factor which determines the climate of a place. Whether a city is equatorial, tropical, sub-tropical or artic; all depends on its Latitude. For instance, Singapore at 1.1 degrees North is a typical equatorial station while Mumbai, India at 19 N is a typical example of a Tropical Station. Latitude also determines the length of day in the summer and winter seasons. In the summer season, the length of the day gets longer and longer as we move from equator towards the North Pole till at North Pole the length of day is six months. In winter however, the opposite holds true, i. e., the days get shorter and shorter as we move away from equator and towards North Pole till at the North Pole it is darkness for six months. It is interesting to note that at equator, the length of day and night is equal throughout the year.
The solar rays of the sun fall obliquely at higher latitudes and therefore are less warm than that which fall at equator. The higher latitudes therefore are cooler than the lower latitudes. Another aspect which is directly related to latitude is the difference in temperatures of the hottest and coldest months. This difference increases as we move from the equator towards the poles. For instance at Singapore ( 1.1 degrees North) this difference is only 1.6 C ( 3 F) whereas in the remote Siberia at Verkoyansk ( 59 N) it is more than 40 C ( 76 F).
The altitude of a place also affects its climate to a great extent. Temperature falls 1 F for every 300 feet or 1. 6 C for every 1000 feet of ascent. So the places located higher up in the mountains enjoy a cool and pleasant climate in summer than those places that are located at low elevation. A striking example is that of Quito , the capital of Ecuador in South America which is located almost exactly on the equator. This city has every month below 15 C ( 59 F) which contrasts with the equatorial average of 27 (80 F). This is only because Quito lies at an elevation of about 10, 000 feet above sea level. The second example is that of Mount Kilimanjaro which lies very close to equator but its peak is covered with perpetual snow. This is all due to its height of more than 19, 000 feet. These examples show how much the climate gets modified by elevation. Actually moving up the mountain is just like moving from equator to poles.
Proximity to Sea.
Proximity to sea makes the climate of a place temperate. The extremes of hot and cold are absent. Winters are warmer and summer cooler than the stations located inland. Compare for instance London ( a station located very close to the English Channel) and Moscow ( a station located very far off from sea. ). In London the average minimum of the coldest month is 2 C ( 36 F) whereas the average minimum temperature of the coldest month at Moscow is -16 C ( 3 F). On the other hand the mean max. of the hottest month at London is 22( 72 F) while at Moscow it is 26 (79 F). The places close to sea are also more humid than those located farther inland. This causes discomfort especially at higher temperatures. Singapore for example experiences a high humidity of 80 percent through out the year and mean max temperature of about 95 F throughout the year. Humidity at such higher temperatures is really suffocating and air conditioners are used frequently to get some relief.
Proximity to Hills.
Proximity to Hills also affects the climate of a place in more than one way. The city located closer to hills is generally wetter, more cooler in winter and less hotter in summer than a station located far away from the hills but on the same latitude. Typical examples are stations of Chandigarh, Ludhiana and Ambala in North-West India and Islamabad and Sialkot in Pakistan. All these stations are located at the foot of the Himalayas. Another very interesting feature of a station located close to Hills is the Katabatic effect or temperature inversion which is most pronounced in Autumn and Spring. In March for example Islamabad ( elevation about 2000 ft above sea level) experiences nights that are 2-3 degrees cooler than that at its nearby hill station of Murree ( elevation 7500 Ft). Although in the day time Islamabad is a 10 C hotter than Murree. This is the reason that during the great summer Islamabd is spared from the oppressive heat of other North Pakistani cities. Likewise at Chandigarh, the Capital of Indian States of Punjab and Haryana, the nights are quite cool as compared to New Delhi which is not close to a mountain system.
Prevailing wind Direction
This factor is also very important and influences the climate of a place to a great degree. To give you an example in July when most of the Northern Hemisphere stations are having their peak summer and very high temperatures are being experienced especially in the Sahara Desert, the cities in North India and Pakistan are enjoying max temperatures that are 10-15 degrees below that of Northern African cities due to the monsoon effect. Compare for example the mean max temperatures of Lahore ( a station having monsoon effect) for July of 36 C with that of Baghdad ( a city lying outside the monsoon belt ) of 43 C. It is interesting to note here that both the cities lie on approximately the same latitude and we expect same temperatures from both.
Prevailing Ocean Current
Prevailing ocean current dramatically alters the climate of a place. In July when most of the inland southern cities of US record a high temperatures of more than 100 F (38 C), the Californian Cost including San Fransisco and Los Angeles enjoy a high temperatures of 75-80 F. This is because a cool pacific current flows past the Californian cost at this time. Similarly in winter when most southern cities which are located inland and on the same latitude as that of San Francisco record a low of less than 32 while San Fransisco has a low of more than 40 F. This is because during winter a warm pacific current flows past the Californian coast. In northern Europe, North Atlantic Drift, a warm current, flows in winter due which coasts as far north as Norway are saved from getting frozen which are all above 55 North whereas lakes near Beijing (39 North) are frozen every year in winter. A current which has the opposite affect than that of the North Atlantic Drift is the notorious Labrador Current which flow in North West Atlantic in winter. This is the same current that was responsible for the sinking of the famous ship Titanic in 1912. This current is a very cold current which brings extremely cold weather to the western coasts of Canada and North- East US while the cities located inland and away from the influence of this current are warmer.
The narration above clearly shows how these six factors are responsible for altering the climate of a place. So the next time we see the climate graph of a city in a book or travel guide we should bear in mind the above six factors.