Rescuers from Britain and the United States have joined efforts to rescue a group of Thai teenagers from a cave system in Chiang Rai Province in northern Thailand. The group, comprising twelve members of a school football team, aged between eleven and sixteen, plus their coach, were trapped in the Tham Leung Cave System by rising floodwaters during a visit on Saturday 23 June 2018 and have not been contacted since, despite the best efforts of local rescue teams. These have now been joined by international cave rescue specialists, including cave divers from the UK, and a team of US military engineers who hope to lower floodwaters in the caves by drilling drainage holes.
A Thai rescue team carrying oxygen tanks in the Tham Leung Cave System in Chiang Rai Province earlier this week. Getty Images.
Most cave systems are the product of erosion, caused by water flowing through soft, porous, limestone systems and slowly eating away at the rock. This means that even cave systems which are not permanently flooded tend to be prone to flooding during wet weather, as is currently the case in Thailand, where, as in other parts of Southeast Asia, an exceptionally heavy Southwest Monsoon, caused by high temperatures over the Bay of Bengal, has lead to widespread flooding this year.
A member of a Thai military rescue team in the Tham Leung Cave System on Wednesday 27 June 2018. Soe Zeya Tun/Reuters.
Monsoons
are tropical sea breezes triggered by heating of the land during the
warmer part of the year (summer). Both the land and sea are warmed by
the Sun, but the land has a lower ability to absorb heat, radiating it
back so that the air above landmasses becomes significantly warmer than
that over the sea, causing the air above the land to rise and drawing in
water from over the sea; since this has also been warmed it carries a
high evaporated water content, and brings with it heavy rainfall. In the
tropical dry season the situation is reversed, as the air over the land
cools more rapidly with the seasons, leading to warmer air over the
sea, and thus breezes moving from the shore to the sea (where air is
rising more rapidly) and a drying of the climate.
Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.
Much of Southeast Asia has two distinct Monsoon Seasons, with a Northeast Monsoon driven
by winds from the South China Sea that lasts from November to February
and a Southwest Monsoon driven by winds from the southern Indian Ocean from March to October. Such a double Monsoon Season is common
close
to the equator, where the Sun is highest overhead around the equinoxes
and lowest on the horizons around the solstices, making the solstices
the coolest part of the year and the equinoxes the hottest. However northern Thailand is largely protected from the Northeast Monsoon by the mountains
separating the country from Myanmar.
