Question

Low pressure is associated with ____________.
(a) clear and sunny day
(b) clear and rainy day
(c) cloudy and rainy day
(d) all of these

Answer 1

Hint: A pressure is a constant physical force imposed against or onto an entity by another entity that it has a contact with. As a result, the weather is affected in a specific way when this physical force or pressure is low on the earth's atmosphere. We need to point out what the associative weather condition is.

Complete answer:
When there is a drop in pressure or pressure becomes low, the air normally rises. The air tends to cool down, also convert into the condensed form, and shapes clouds as the air has risen. Depressions are the general term that areas of low pressure are called with.

When warm air encounters cold air, depressions arise. A 'front' is the boundary of meeting for the warm and cold air. Storm and rain are normally present along the front. This is when cold air comes into contact with warm air so warm air starts to cool off and condenses.

Let us examine each option now;
If we look at option (a) clear and sunny day it is incorrect; this is because when there is a lower pressure on the atmosphere, the formation of depressions take place. When there is a depression the air molecules tend to undergo condensation due to the meeting of cold and warm air and so clouds get formed. Also condensation leads to water drops in clouds as a result of which rain occurs. So the day is definitely neither clear nor sunny.

Taking option (b) clear and rainy day is also incorrect since; the day being rainy is a fact in areas where depression occurs due to low pressure, since condensation takes place. But the day cannot be ‘clear’ because condensed air forms clouds that fill up the sky so the day would not be clear.

Then option (c) cloudy and rainy day is correct since in areas or lower pressure or depressions the conditions required to form clouds are met. So definitely the day should be cloudy. Also in areas of depression there exists a condition where the warmer air meets with the cooler air so condensation takes place forming rain. So the day would be both cloudy as well as rainy.

And option (d) all of these is an incorrect option; since in two of the options one or more among the conditions are not caused by low pressure that is clear or sunny days. Also only one of the options has the right conditions required when the atmosphere is under a lower pressure that is rainy or cloudy day.

Therefore the option giving the correct answer is option (c) cloudy and rainy day.

Note: Since we now understand how low pressure affects the atmosphere, we may investigate a high pressure system. It is cooler air that is heading into the earth's surface from the upper layers of the atmosphere. As the air sinks, it becomes heavier, and all water evaporates into the mass of air. The weather as an outcome is fair, stable, and dry, as no water is available to form cloud structures for rain.