The recent heatwave predicted by the Pakistan Meteorological Department was spotted well before time, as a huge low pressure area was developing over and around Karachi with a high pressure area in the northwest of Karachi around Panjgur in Balochistan.
We all know that the wind blows from high pressure areas to low pressure areas, so winds coming from the northwest towards Karachi are very hot because the temperature in Balochistan in the summers is very high. Another factor which has contributed to this heat wave is the absence of sea breeze and high humidity which is normally present in the coastal areas like Karachi.
Source:- Aviation Weather by FAA USA (Book)
It is to be noted that land breeze and sea breeze are essential elements in the coastal areas. The land gets hot as the sun rises and its temperature increases. The sea does not get that much temperature during the day as evaporation starts over the sea, which is a cooling process, so there is a temperature difference exists between land and sea. The low temperature over the land creates a low pressure and high temperature over the sea builds a high pressure area, so the wind starts blowing from the sea to the land.
Sea breeze being cooler than the adjoining land area, keeps the temperature to a lower level. This process is reversed during the night, and wind starts blowing from land to sea. The present heatwave is due to the absence of land and sea breeze and high percentage of humidity in the atmosphere which makes it difficult for the human body to bear high temperature in these circumstances.
It is very important to avoid this heatwave by taking precautions in the extreme weather.
Do not allow your body to dehydrate and keep yourself under the shade to avoid scorching heat.