Why? Thermohaline circulation is the movement of deep currents, which form at the surface of the ocean in high latitudes (near the poles) where they become cold and dense, so they sink.

Oceanic currents are driven by three main factors:

• The rise and fall of the tides. Tides create a current in the oceans, which are strongest near the shore, and in bays and estuaries along the coast.
• Wind. Winds drive currents that are at or near the ocean’s surface.
• Thermohaline circulation.

Dense water sinks below less dense water. This is the principle that drives the deep ocean currents that circulate around the world. A combination of high salinity and low temperature near the surface makes seawater dense enough to sink into the deep ocean and flow along the bottom of the basins.

Surface currents can flow for thousands of kilometers and can reach depths of hundreds of meters. These surface currents do not depend on weather; they remain unchanged even in large storms because they depend on factors that do not change.

Surface wind-driven currents generate upwelling currents in conjunction with landforms, creating deepwater currents. Currents may also be caused by density differences in water masses due to temperature (thermo) and salinity (haline) variations via a process known as thermohaline circulation.

Surface ocean currents flow in a regular pattern, but they are not all the same. Some currents are deep and narrow. Other currents are shallow and wide. Currents are often affected by the shape of the ocean floor.

In contrast to wind-driven surface currents, deep-ocean currents are caused by differences in water density. The water cools as it moves into higher northern latitudes, and the more it cools, the denser it becomes. In the North Atlantic Ocean, near Iceland, the water becomes so cold that sea ice starts to form.

Latitude or distance from the equator – Temperatures drop the further an area is from the equator due to the curvature of the earth. Altitude or height above sea level – Locations at a higher altitude have colder temperatures. Temperature usually decreases by 1°C for every 100 metres in altitude.

At higher elevations, air molecules are spaced farther apart, meaning the air is less dense. The air is less able to trap heat from the Sun, so temperatures are cooler. At lower elevations, air molecules are closer together, meaning the air is more dense. The air is better able to trap heat, so temperatures are warmer.

Near the Earth’s surface, air gets cooler the higher you climb. As you climb a mountain, you can expect the air temperature to decrease by 6.5 degrees C for every 1000 meters you gain. This is called the standard (average) lapse rate.

As altitude increases, the amount of gas molecules in the air decreases—the air becomes less dense than air nearer to sea level. High-altitude locations are usually much colder than areas closer to sea level. This is due to the low air pressure.

The cold weather is caused by “amihan,” or cool northeast monsoon season that prevails between October and early March, Pagasa said. Last year, the coldest temperature recorded was 9.4°C degrees, the lowest so far in the last three years. The coldest temperature ever registered here was at 6.

January

When is the best time to go to Baguio?

• The best months for good weather in Baguio are January, February, March and December.
• On average, it is hot all year round.
• The rainiest months are July, August and September.

The City of Baguio is located high up in the mountains in the province of Benguet, Luzon. Air at higher elevations is cooler because the pressure is low. That’s why Baguio is really cold. The temperature from 46 years ago qualifies as the lowest temperature the city ever recorded so far.

It is generally safe to do so. While at it, it pays to know that Baguio City was declared one of the safest cities in Southeast Asia in 2018. The already-low crime rates had a 41.8% decrease in 2018 compared with that of 2017. Not just in Baguio, but the entire Cordillera region.

Baguio City