Changes in the Atmosphere: Observing Changes in Humidity

Hazy Sunrise June12, 2015 Lisa A. Wisniewski

Hazy Sunrise June12, 2015
Lisa A. Wisniewski

Though summer has not officially arrived in my area, we have been experiencing summer-like temperatures and weather.  Yesterday, the high was 90°F, ten degrees above normal.  Add to this a humidity level of 90%, and you have tropical type conditions.   After pedaling three miles on my bike yesterday, I felt sweaty, more tired than normal, and a bit dizzy.  This experience made me think about humidity and the effects it has upon human beings and nature.

What Is Humidity?

The basic definition of humidity is the amount of water vapor in the air.   More water vapor in the air equates to a higher humidity level.  Less water vapor in the air equates to a lower humidity level.  The humidity level may be measured using a device called a hygrometer.

There are different types of hygrometers.  Some are mechanical, activating a spring to provide a reading.  Others may be electrical or digital, using readings and changes to these readings as an indication of humidity level.  Still others may consist of mirrors or thermometers that react to moisture in the air.  The type of hygrometer used depends upon the type of humidity being measured.

Types of Humidy

Relative humidity is the amount of water vapor in the air compared to the amount of water vapor the air is capable of holding.  Meteorologists often talk about this type of humidity and express it as a percentage.

Dew point temperature is the air temperature at which saturation of the air by water vapor occurs.  When you see morning dew on the grass, mist or fog in the air, or tiny water droplets on the sides of cups holding cold drinks, you know the air is saturated.  The dew point is given as a temperature instead of a percentage.

Effects of Humidity

Humidity has different effects upon humans, animals, plants, and common objects.  Among these effects:

  • Humidity retards evaporation of sweat from skin, affecting the body’s ability to cool itself. This lack of cooling may result in chemical imbalances, heat-related illnesses, and even death.
  • Humidity causes hydrogen bonds to form between water molecules and proteins in hair. This causes hair to curl or become frizzy.
  • Humidity affects turgor pressure in plants. Plants that can tolerate the additional moisture thrive in humid conditions.  Plants that prefer more arid conditions may wilt and die.
  • Humidity promotes the growth of some molds and mildews. Humidity levels above 50% create conditions that can foster mold and mildew growth.  This is why many homes are temperature controlled.
Condensation, a form of water vapor Lisa A. Wisniewski

Condensation, a form of water vapor
Lisa A. Wisniewski

Humidity and Storms

Moisture and rapidly warming air are the two conditions that make thunderstorms possible.   Since the sun warms the air and is more prevalent in summer, we see more thunderstorms during this time of year.

The collision of water droplets and ice particles causes portions of clouds to become positively and negatively charged.  As charges are exchanged and water molecules move from the upper to lower levels of the atmosphere, and electric field is created.   A strong electric field may create a path for the charges, resulting in lightning.

Rapid heating caused by lightning and rapid cooling in the atmosphere creates sound waves.  The sound waves are what we call thunder.

Storm clouds forming Lisa A. Wisniewski

Storm clouds forming
Lisa A. Wisniewski

How to Determine Humid Conditions

One of the easiest ways to determine humidity is by looking outside.  If the air is thick and visibility is low, it is humid.  If the sky is clear and visibility is high, humidity is very low in the atmosphere.

Some weather forecasters use the term “3H’s” to define when the weather is hazy, hot, and humid.  Typically, these conditions are associated with summer weather patterns.

There are also weather information websites and statistics available that state temperature, humidity, and dew point information.

Heat index charts illustrate how the combined effects of heat and humidity feel to the human body.  Often, news stations report humidity index levels to help warn of the dangers of high heat index levels.

Nature’s Balancing Act

In a way, humidity is one of nature’s ways of keeping things in balance.  As warm and cold air masses move from one location to another, energy is given off in one area and absorbed in another.  The transition of energy creates conditions suitable for both growth and decay.

Observing all these changes is one way to keep the mind and body in balance as well.  Each day presents opportunity for growth, knowledge, and understanding to help us through life.  As we gain balance and perspective, we become more in tune with nature and its many changes.

Sun after a storm Lisa A. Wisniewski

Sun after a storm
Lisa A. Wisniewski

Resources and Related Links

Dew point temperature –
Heat index chart –
Humidity –
Humidity and mold –
Humidity and storms –
Humidity’s effect upon hair –
Humidity’s effect upon humans –
Humidity’s effect upon plants –
Hygrometer –
Relative humidity –


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