Good morning to all my fellow colleagues and readers of my blogs on zoomradar. I am going to write about something that seems to be gripping our planet recently, and that is Heat waves and corresponding drought. I will provide informative material that covers how heat waves develop, intensifies, and spreads to certain locations. The health risks associated with heat and drought, and ways to deal with a heat wave when it occurs in you’re area, and infamous heat waves in the past


Heat and drought in tandem are the number 1 killer of living beings on this planet that embodies humans, animals and plants. Heat has no universal definition, but the World Meteorological Organization says when daily maximum temperatures exceed 5 degrees Celsius and or 9 degrees Fahrenheit on average. The National Weather Service defines heat waves as a period of at least 48 hours which neither the overnight low nor the daytime high falls below the heat stress threshold of (80 degrees at night and 105 degrees during the day).

A. Why is Heat Hard to Define- Heat = stress, and people have different tolerances to stress. It is a silent killer, unlike lightning, tornadoes, hurricanes, derechoes, or severe thunderstorms which all are dramatic events. Heat and drought do their damage silently like ninjas. That is why it is so important to take precautions when a heat wave is forecasted for you’re region. These steps include : when working outdoors take frequent breaks, drink plenty of water, no sugary or alcoholic beverages because that will cause further dehydration, and periodically get into an air conditioned building to cool off body core temperatures.

B. Extreme Heat Warnings and Heat Index –

I am sure we have all heard our local Meteorologists have a forecast for heat. This heat forecast is called the heat index. What is this? How does it affect/effect me? Well I have good news I am going to explain it to you to better understand what we are dealing with together in terms of the dangers of heat. The Heat Index(HI) is and “apparent temperature”. The heat index is provided in degrees Fahrenheit. Forecasters calculate what the temperature and Relative Humidity will be for a given day and then forecast a heat index forecast. For example, if you had a 85 degree expected high temperature and it was really humid say 85% relative humidity the heat index would be 99 degrees Fahrenheit. NOAA has a Heat Index calculator the public can use= http://www.hpc.ncep.noaa.gov/html/heatindex.shtml  . We know that with increasing humidity the more uncomfortable we feel, it feels sticky and muggy. Why? Here’s why, when it is relatively dry low RH say 30% and temperatures hit 90 degrees, our bodies produce sweat, the sweat evaporates causes a “cooling effect” so we feel comfortable.(remember from the last couple of blogs I mentioned evaporational cooling, same concept here only this pertains personally to us). So when we have 85% RH our bodies can’t cool off through evaporation, and we keep sweating and sweating with no desired results. That is why it is imperative to take the precautions stated above in heat waves. Many parts of the country have had heat indexes above 100 degrees this past month due to High Heat and High Humidity. Fortunately for us who live in the south we have the luxury of air conditioning, however, places in the North, like the Pacific Northwest and Northern Tier of our country don’t so mitigation efforts are needed to combat the heat. Now Heat Index as effective as it is, is not universal, for example, Heat index is subjective based on how you feel, people have different capacities to handle heat and the heat index doesn’t consider wind or shade.

This heat index chart provided by weather.about.com shows the danger of heat and the combination of high humidity can do to us.



A. Hot stable air persisting for days

B. Through this persistence of stable air, an abnormally strong ridge of High Pressure develops and intensifies throughout the whole profile of the atmosphere, from the upper levels to the surface.

C. Little or no wind to mix the air, thus stagnant polluted air

D. Increased pollution and Ozone at the surface where we live due to stable conditions

E. Potent Heat waves and droughts are caused by Subtropical Ridges located between 30-35 degrees North Latitude in the summer. These high pressure systems compress the air and heat the surface through adiabatic warming, which is warming due to compression of air.

F. As the High Pressure systems intensify and get stronger they can spread, move and build from one place to another. For example take this heat wave in the Southeast this late spring and early summer. The heat originally started in Florida and South Georgia, persisted for days and days and eventually built and moved into the entire southeast for the entire month of June. The same concept out West. The Thermal Low in conjunction with a High pressure system out West in Arizona, New Mexico and Southern Utah and Nevada persisted for days and days and eventually intensified and now dominates most of the Western 1/3 of the country. The pacific northwest has to be on alert as well as Alaska, I can’t forget about our Friends up north. The key to identify where a heat wave is going to develop is in the Polar front Jetstream or (PFJ). If you are in a location south of the Jetstream you will likely experience above normal heat and possibly heatwave conditions, conducive for High Pressure Ridging. Subsequently, if you are situated North of the PFJ or Jetstream you will experience cooler than normal temperatures, and very pleasant conditions.

Here is a great depiction by weatherbug.com of high pressure, sinking or compressing air, little or no clouds, high evaporation rates, no vegetation to cool ground, and a sun angle that is ridiculously high around 90 degrees. All of these factors if they persist for days and weeks lead to severe heat waves and droughts.


A. SWEAT – Sweat is an important part of humans to cool off during heat, remember what I had mention above in relation to heat and humidity. It is much harder to cool off during high heat and high humidity than high heat and low humidity. This because evaporation is a cooling effect for the atmosphere and our bodies. For example water has a high caloric factor. when we evaporate I gram of sweat that process of evaporation is requiring 600 calories and balance is present. If high humidity and heat are occurring blood flows to our extremities and we keep seating with little or no evaporation, thus thwarting cooling for us. Thus putting us at risk for Heat Related Illnesses.


A. Heat Cramps– We get Heat Cramps and Muscle Pains when heat index is between 90-105 degrees according to NOAA with prolonged exposure and physical activity to these conditions. This is an early sign of trouble brewing.

B. Heat Exhaustion – which is a mild form of shock can cause Dizziness, Confusion, Weakness, and Vomiting. This is a serious condition and should be treated as one. I once being a Phys Ed teacher is South Florida had to modify programs for students due to the heat by going indoors and or limiting outdoor activities. I have witnessed heat exhaustion and it is very serious. Heat exhaustion can occur between 90-105 degree heat index of prolonged exposure and physical activity and definitely occurs at 105-129 degree heat index with prolonged exposure/physical activity

C. Heat Stroke – The Most serious of all heat related Illnesses. This is where our bodies loses the ability to regulate temperature. Our Body temperature can exceed 105 degrees Fahrenheit, which is called HYPERTHERMIA – which can be fatal!

This cartoon picture shows the signs of heat fatigue, which can occur rapidly, and lead to heat stroke if precautions are not taken.


A. Geography – Where?

  • Urban Settings High Risk
  • Midwest/Northern Tier States
  • Lack of Air Conditioning/Cooling
  • Not Acclimated to heat in these areas

B. Urban/Rural –


  • Low Albedo – which means asphalt and brick absorb most of the Sun’s rays and energy causing and enhanced heat index
  • Low winds – less mixing and more pollution
  • Industry – More Heat produced here
  • URBAN HEAT ISLAND- urban areas are usually 5-10 degrees warmer than surrounding rural areas during heatwaves


  • Higher Albedo – Rural areas reflect more of the Sun’s energy and UV rays back into space
  • Wind – More winds here to mix the air and less pollution
  • No UHI – No Urban Heat Island


A. Chicago Heat Wave 1995 – Daily Lows and highs in July’s Heatwave

  1. July 11: 73 – 90 degrees Fahrenheit
  2. July 12: 76 – 98 degrees Fahrenheit
  3. July 13: 81 – 106 degrees Fahrenheit
  4. July 14: 84 – 102 degrees Fahrenheit
  5. July 15: 77 – 99 degrees Fahrenheit
  6. July 16: 76 – 95 degrees Fahrenheit
  7. July 17: 73-90 degrees Fahrenheit

Contributing factors to this Heatwave

  • Urban Heat island
  • Strong High Pressure on all atmospheric profiles plus strong inversion at 10000 feet.
  • Absence of any wind
  • High pollution levels
  • As a result 465 people died in Chicago and 800 people Nationally because this heat wave spread

B. France 2003 –

  • Genuine heat epidemic which lasted 30 days!!!
  • French health ministry reported 3,000 people have died due to this heatwave
  • One of worst natural disasters in French History
  • By the end of the summer some 50,000 people perished!! That’s crazy everyone!!


This is a diagram by accuweather.com that depicts one of the reasons why heat builds and intensifies. Subtropical High/Continental Highs develop, build and intensify and MOVE!!


A. Hydration – If a heat wave is forecasted for you’re area please drink plenty of fluids – water some Gatorade but not too much. Please avoid caffeinated drinks, alcoholic beverages, and Milk, these will dehydrate you.

B. Stay Cool – If you are outside or if you work outdoors and if you have a chance to get into a building with air conditioning do it. Also, take frequent breaks, stay hydrated, keep a moisten towel with you, wear a hat covering you’re face, and cool clothing like white clothes that have a high albedo. Wear a Sunblock with a high UV protection like 50+.

C. Awareness – Please check on the poor and elderly especially those at most risk to the heat. This act of giving helps others and makes you feel good about yourself.

These two graphic images by Bloomberg.com and ecoaffect.org depict just how dangerous heat can be. Well that’s all I can do today I know I didn’t get to drought but I will next time on my next blog. Well that’s it, stay well, beat the heat, and provide some feedback. Thank you all.


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