Winter: the coldest season
Changing the time frame Most people think that the coldest season starts from the winter solstice, but in fact there are two definitions of winter.
Astronomical winter-most people think that winter is determined by the position of the earth around the sun, ranging from winter solstice to vernal equinox. The winter solstice marks the time when the sun directly crosses the equator. According to the data of National Weather Service (NWS), the northern hemisphere is around 65438+February 2 1, and the southern hemisphere is around June 2 1. This is the shortest day in a year, and all cultures in the world notice and celebrate it. [Photo album: amazing snow scene]
According to the northwest region, on the solstice in winter, the corresponding poles are tilted about 23.5 degrees from the sun. On that day in the northern hemisphere, the North Pole is farther away from the star that produces heat, and the southern hemisphere that experiences summer is closer.
However, anyone who often engages in winter sports may tell you that the weather in winter often drops before mid-February or mid-June. According to the data of National Oceanic and Atmospheric Administration (NOAA), meteorological winter comes faster in the three months from February to March. It is based on the annual temperature cycle and calendar, not the earth's journey around the sun.
Winter in the Northern Hemisphere People living in the Northern Hemisphere are more likely to experience cold winters than those living in the Southern Hemisphere. In fact, the coldest countries in the world are all located in the northern hemisphere. According to Earth and World, these countries include Kazakhstan, Russia, Greenland, Canada, the United States, Iceland, Finland, Estonia and Mongolia. Although Antarctica is not a country, technically speaking, Antarctica in the southern hemisphere is the coldest region on earth. )
So why are many countries in the northern hemisphere much colder than those in the southern hemisphere? This is because there are several main differences between the two hemispheres in the factors that affect the climate: the size of the land, the distance between the land and the polar regions, and the coverage of the ocean.
First of all, there are many lands in high latitudes in the northern hemisphere, even in the Arctic Circle, such as Greenland, northern Norway, Sweden, Finland, Iceland, and tundra in North America, Europe and Asia. In contrast, the larger land in the southern hemisphere is closer to the equator, and no country is located above or below the Antarctic circle-only the frozen Antarctic continent.
Another important thermostat is the ocean. According to Springer (20 12), the ocean covers 8 1% of the southern hemisphere, while the northern hemisphere only covers 6 1%. All this water stores and conducts heat better than land, which helps to maintain a higher and more stable temperature.
Winter brings many changes to the world around us. In winter, some animals migrate, which means moving to another area in one season. Animals usually go south to the warm Duri area, and the Little Ice Age from14th century to19th century may be the most memorable extremely cold period. According to a study published in Geophysical Research Letters, several volcanic eruptions triggered the expansion of Arctic sea ice and triggered a chain reaction of global temperature drop. According to the report of the History Channel, climate is related to many trends and events, including the Black Death, the 30-year War, political persecution on both sides of the Atlantic, the French Revolution and the invention of bicycles. The "cold winter" of "keeping warm" will quickly bring life-threatening medical conditions, such as hypothermia. According to the Mayo Clinic, hypothermia means that the body temperature drops below 95 degrees Fahrenheit (35 degrees Celsius). Cold temperature and wind chill can make people's body temperature drop in a few minutes.
Low temperature can also lead to frostbite and freezing of skin and tissues. Cold temperature is only one factor of frostbite susceptibility. Nicholas, chief medical officer of MeMD, a web-based medical service provider, said: "Other factors may also play a role, including the age/size of the individual (for example, children get sick faster) or the individual's poor circulation to distant body parts (for example, hands/fingers/feet/toes)." Dr Nicolas Lorenzo said,
Low temperature and frostbite can be avoided. It is important to keep all skin covered and dry in cold weather. Once a person has hypothermia or frostbite, the first treatment is to reheat the patient.
This famous painting "The Frozen Thames" by 1677 shows that a huge river in England was frozen into a solid during the Little Ice Age. (Commons) Winter Quotations "Now is the winter we are dissatisfied with." -william shakespeare
"If winter comes, can spring be far behind?" Percy Bysshe Shelley
"Laughter is to drive away the winter sunshine from people's faces." victor hugo.
"Winter is not a season, but a profession." Sinclair Lewis
Winter is a comfortable, delicious and warm season, a time for friendly hands to touch, a time for chatting by the fire, and a time for "going home". "-Edith Sitwell.
"You can't live too much in winter." Robert Frost
"Winter is a natural saying, it is' yours'. Robert byrne.
"What are the benefits of warm summer? No winter cold brings it sweetness. " John steinbeck.
"The melancholy voice is a winter night. Virginia Woolf
"My recession will last into the winter." Bob Uckel
Additional reporting by Life Science writers Tracy Peterson and Elena Bradford.