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Beat the Heat
A meteorologist forecasting the weather for the day states that a
warm, sunny afternoon is ahead. As soon as a person steps
outside, the body is ready to adjust itself for comfort. Minute by
minute, the body can rely on its inner thermostat to stay in tune
with the surrounding environment.
The body is sensitive to the
environmental temperature, a physical
property that expresses degrees of hot
and cold. On a molecular level,
temperature has to do with the speed of
moving atoms. Molecules move more
rapidly in the heat and slow down in the
cold. Temperature can be measured with
a thermometer using one of three distinct
scales: Fahrenheit, Celsius, or Kelvin. A
temperature in one unit can easily be
converted to another unit using a
mathematical formula. For instance, 32°
F is equal to 0° C, and both are equivalent
to approximately 273 K.
A temperature in one unit can easily be
converted to another unit using a
mathematical formula.
Factors Influencing Temperature
Temperature can feel different depending on the humidity, or
moisture in the atmosphere. Relative humidity is the percentage
of water vapor in the air compared with how much water vapor
the air can hold at that temperature. When temperatures rise,
liquid water molecules vibrate fast enough to change phases and
become water vapor. In other words, water evaporates. When
the temperature cools down, the molecules lose energy, slow
down, and condense into liquid form. The following equation
defines relative humidity:
Actual Vapor Density
× 100%
Relative Humidity =
Saturation Vapor Density
During a weather forecast, meteorologists often talk about the
temperature-humidity index, commonly called the "heat index."
The number is a cross between the air temperature and the
relative humidity, pinpointing how the body may feel due to
both factors. If the temperature is 90° F and the relative
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Beat the Heat
humidity is 60%, the combination will actually make the body
feel as though it is 100° F outside.
It is important to understand that the heat index assumes that
an individual is standing in a shady place and there is a light
breeze. These conditions may not always be the case. Higher
winds can cool down the body, particularly when the skin is wet.
Evaporative cooling is when wind causes moisture on the skin to
turn into vapor, taking heat away from the body in the process.
Standing in direct sunlight can make the heat index increase by
15° F. On a particular day, the heat index may be 95° F. The
temperature will feel much hotter to a person who is watching a
parade in full sun than to someone who has just climbed out of a
pool and is sitting under an umbrella in the shade.
Another factor that influences how hot it
feels is clothing. Layers trap heat between
the fabric and skin. Therefore, on hot days,
it is best to put on loose-fitting and
lightweight outfits. Wearing light colors also
helps because light colors reflect heat, while
dark colors absorb heat.
In a hot environment, sweating allows the
body to lower its temperature. The
hypothalamus is the part of the brain that
works like a thermostat and tells the body
when to start sweating. Sweat glands on the
skin respond to the signal by spewing out
Sweating allows the body to lower its
perspiration through pores, or tiny
temperature when the body gets too
openings. This natural cooling method
hot.
relies on evaporation to carry heat away
from the body. However, excess sweating, such as during
strenuous exercise, can cause an individual to lose too much
water and salt. In this case, it is necessary to rehydrate with
water or sports drinks. But caffeinated beverages should be
avoided.
Humidity plays a role in how well the body can cool itself
through sweating. A high relative humidity hinders evaporation
because the air is already saturated with water vapor. When the
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Beat the Heat
sweat cannot vaporize into the air, the body cannot keep itself
cool.
The Dangers of Heat
As the heat index rises above 90° F, a fun day in the sun can
turn into a dangerous situation. A
person can suffer a number
of heat-related illnesses. These
include sunburn, muscle cramps,
heat exhaustion, and heatstroke.
Most people are familiar with
sunburn and how the skin becomes
red and tender. In a bad case of
sunburn, the skin can swell and
blister and may even bring on a
fever or headache. Excessive heat
can also cause muscle cramps,
which are spasms that a person
feels in the legs or abdominal
While sunbathing on the beach, a person
muscles. Symptoms of heat
should wear sunscreen, limit the amount of
time lying in the sun, and swim to cool down.
exhaustion include sweating
profusely, pale skin, and fainting.
Heatstroke is a life-threatening condition. The body can no
longer sweat to keep itself cool, leaving the skin hot and dry.
While the heart beats rapidly, the body temperature rises to
106° F or higher. If the person does not receive immediate
medical assistance, heatstroke can lead to death.
Heat has claimed more lives than natural disasters. To stay safe
during unusually hot days, it is crucial to take precautions, such
as staying inside and drinking plenty of water.
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