When we talk about meteorology, there are various types of phenomena that can occur annually, each with its own unique origin and characteristics. Today we're going to talk about the dog days of summer . This name evokes images of dogs, and from this association seems to come the expression "it's a dog day." However, dogs have little to do with the meaning of the dog days. The dog days of summer are a period of intense heat and refer to the star Sylvio in the constellation Canis Major, which becomes much brighter in the sky during this time.
In this article we are going to explain what canicula is, what its characteristics and origin are.
Key features
When summer arrives, the constellation Sirius reaches a maximum brightness of one billion in the sky. The appearance of Sirius used to make our ancestors tremble, as it meant it was going to be very hot. It was known as the scorching one. It was thought that this constellation, being brighter, emitted more heat in conjunction with the sun. Together, they generated a heat infusion that made those days the hottest of the year. Nowadays, the hottest days no longer coincide with the heliacal rising of Sirius, which is observed in early September. However, the term "dog days" has become so ingrained in tradition that it is still used. To learn more about its meaning, you can consult this article on what the dog days of summer are.
Canicula period in Spain
The dog days are statistically the hottest period of the year. In Spain, the hottest days of the year are spread between July 15th and August 15th. Its start doesn't coincide with the beginning of summer, but rather falls in the middle. This is mainly due to three factors. Let's analyze the main factors that cause the summer heat to not correspond to the astronomical summer:
- In these dates the sun shines in the northern hemisphere more perpendicular than ever. This causes the inclination of the solar rays to be direct. The inclination of the sun's rays is much lower in winter, so it transmits much more radiation. After a few weeks with this scenario, the ground overheats and distills heat. Let's not forget that if we add to this the heat island effect of cities, they can become unbearable heat.
- The sea has higher temperatures and its thermoregulatory action begins to languish. We know that the sea takes longer to acclimatize to reach the temperatures of the atmosphere. The air becomes colder or warmer faster than the sea. Therefore, it must be taken into account that in order for the sun's rays to heat the entire mass of the ocean, sufficient time must pass for it.
- A few weeks earlier, having lower records on its surface, it refreshes the atmosphere through the sea breezes and at that moment not so much anymore. To better understand this phenomenon, you can read about the sea breeze and its influence on the climate.
Heat waves and canicula
It's important to understand that a dog days of summer (canicula) is not the same as a heat wave. While the former is a statistically hotter period that occurs around the same time each year, heat waves are more unpredictable and random. It's true that they often coincide. It's normal that, combined with a statistically hotter period, they can be associated with heat waves. This heat raises average temperatures, making them statistically hotter. For example, between July 23rd and 25th, 1995, a heat wave recorded temperatures of 46 degrees Celsius at the observatories in Seville and Cordoba . These values are extraordinary, but not far from the 43-44 degrees Celsius that are typical for this time of year. These temperatures are usually seen in the Guadalquivir Valley.
In the height of summer, it's normal for temperatures to rise, especially in cities. The midsummer heat wave, also known as the "dog days of summer," is a period of intense heat that typically lasts up to 40 days and is characterized by the most sweltering temperatures. For more information on heat waves, you can consult this link.
Among the characteristics that we have of the canicula we see the following:
- Temperatures above 37 degrees: These temperatures can frequently generate some health problems for the most vulnerable people. Although heat waves are more dangerous to be faster, heat waves can be more persistent.
- Decrease in rainfall: high temperatures prevent the generation of rain clouds due to the rise of hot air and a decrease in the environmental thermal gradient.
- Excessive air heating: the air becomes so hot that it circulates from one place to another more quickly.
- Totally clear sky: This is related to the above. High temperatures reduce the formation of rain clouds.
High temperatures
During the dog days of summer, it's common to find several cities in Spain where temperatures reach or even exceed 40 degrees Celsius. Some forecasts predict temperatures as high as 45 degrees, especially when combined with the effects of a heat wave during this period. These extremely high temperatures are often accompanied by wildfires and droughts. Droughts are severe periods that affect vegetation and water resources for human use. For a broader understanding of the increase in wildfires, it is recommended to read about forest fires.
Of course, it should be mentioned that climate change is worsening the canicula situation every year. That is, there is a higher average temperature during these 40 days than the canicula usually lasts.
Some of the tips that are given to combat these days of intense heat, are the following:
- Avoid the direct exposure to the sun, especially at noon, which is when the sun's rays have a lower degree of inclination and the temperatures are higher.
- Drinking water continuously to avoid dehydration.
- Eat fresh food
- Apply sun cream to avoid burns
- Use umbrellas, Light clothing and a hat to protect yourself from the sun.
I hope that with this information you can learn more about the canicula and its characteristics.