Clusters of redbud blossoms cover the tree’s branches in the early spring, before the leaves begin to unfold.
Credit: © Thinkstock

Spring has sprung! Today, Monday, March 20th, is the vernal equinox. The equinox is the official marker of the spring season in the Northern Hemisphere. The equinox occurs when the sun is directly above Earth’s equator. When the sun is in this position, all places on Earth receive approximately 12 hours of sunlight. The term equinox comes from a Latin word meaning equal night.

Many people in the United States are welcoming spring with piles of snow outside their front door! Unseasonal and abnormal storms have hit California and the northeast United States. Heavy rain, snow, hail, and even tornadoes have hit California in the last two months. The flooding has broken levees in some communities in northern California, raising fears of even more damage. A nor’easter hit New England on Tuesday, March 14th, after an unusually quiet winter, dropping nearly 28 inches (71 centimeters) of snow in Vermont and Massachusetts. A nor’easter is a powerful storm coming from winds going northeast that produces a lot of precipitation. Many people throughout the United States are keeping their snow shovels, boots, and parkas out for a few more weeks!

A snowstorm in the Boston area left two feet of snow. Credit: AP Photo

The equinoxes occur on March 19, 20, or 21 and on September 22 or 23. In the Northern Hemisphere, the March equinox marks the start of spring and is often called the vernal equinox. The position of the vernal equinox is called the first point of Aries. The word vernal means of spring. The September equinox marks the beginning of autumn and is called the autumnal equinox. The seasons are reversed in the Southern Hemisphere.

The time interval from the March equinox to the September equinox is longer than that between the September equinox and the next March equinox by several days. This time difference results from the earth’s elliptical (oval-shaped) orbit around the sun. The earth moves faster in its orbit when it is closer to the sun. The distance between the earth and the sun is shortest in January. Therefore, the earth completes the semicircle from the September equinox to the March equinox faster than it does the opposite semicircle.

The equinoxes are the two moments of the year when the sun is directly above the equator. As Earth moves in its orbit around the sun, the position of the sun changes in relation to the equator, as shown by the dotted lines in this diagram. The sun appears north of the equator between the March equinox and the September equinox. It is south of the equator between the September equinox and the next March equinox. Credit: WORLD BOOK diagram

Historically, the year began with spring in many cultures. Evidence of this practice in ancient Rome remains part of the modern calendar. Counting March instead of January as the first month of the year, we find that September, October, November, and December are the seventh, eighth, ninth, and tenth months. The prefixes sept-, oct-, nov-, and dec- come from the Latin words for 7, 8, 9, and 10.

Spring looks different around the world. The Northern Hemisphere has spring weather from late March through May. In the Southern Hemisphere, spring weather begins in September and lasts through November. The number of daylight hours increases during spring, particularly in the polar regions, and the temperature rises. Nature awakens in spring. Flowers bloom, and hibernating animals leave their winter sleeping places. Many cultures have festivals that celebrate the arrival of spring. Find your own way to celebrate spring this year. Spring is a new beginning, enjoy the flowers, longer days, and warmer weather!

June 21, 2019

Today, June 21, is the first day of summer, and people in parts of the Midwestern and Southeastern United States can say goodbye to a stormy spring that included record flooding and an unusual number of powerful tornadoes. Beginning in March, snowmelt and repeated heavy rains overflowed the Arkansas, Mississippi, Missouri, and other rivers. Tornadoes ravaged many areas in March and April, and in the month of May alone, an astounding 362 twisters touched down in 12 different states. The combined spring storms killed 64 people and caused billions of dollars worth of damage.

Mississippi River floodwaters cut off a highway at the Illinois-Missouri border on May 30, 2019. Spring storms ravaged many parts of the Midwest and Southeast in 2019. Credit: © Scott Olson, Getty Images

An unusually cold winter resulted in large snowfalls and frozen ground throughout the Midwest. In March, melting snow added large amounts of water to streams and rivers. Torrential downpours then followed, resulting in floods that affected Arkansas, Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma, South Dakota, and Wisconsin. Six people died in the regional flooding, and the waters caused some $8 billion in damage. Powerful thunderstorms and flooding continued in April and May, spreading damage to the states of Florida, Kentucky, Louisiana, Mississippi, North Carolina, Tennessee, and Texas. In some states, more than a month’s worth of rain (compared with the average) fell in a single day. Saturated fields prevented many crops from being planted, and many existing crops were severely damaged.

In early March, tornadoes first struck in the Southeast, killing 23 people and causing extensive damage in parts of Alabama, Florida, Georgia, and South Carolina. In April, tornadoes killed 20 more people in the states of Arkansas, Louisiana, Mississippi, Missouri, Oklahoma, and Texas. Then, in May, 362 tornadoes killed 15 people across the Midwest. A number of the tornadoes rated EF4—wind speeds of 166 to 200 miles (267 to 322 kilometers) per hour—on the Enhanced Fujita Scale, used to measure a tornado’s intensity. (EF5, with winds over 200 miles (322 kilometers) per hour, is the highest rating.) Destruction was substantial in Dayton, Ohio, and Linwood, Kansas, but no people were killed.

The Midwestern and Southeastern United States are accustomed to bouts of severe spring weather, but this year’s storms were abnormally abundant and strong. The increases in bad weather—in both winter and spring—aligned with what scientists expect as the world’s climate continues to change. As average global temperatures rise, air becomes saturated with moisture, resulting in higher amounts of precipitation. Scientists at the National Oceanic and Atmospheric Administration have warned of increasing episodes of severe weather because of climate change.

March 11, 2016

Very heavy rainfall developed in some Southern States during the afternoon of March 9. By the morning of March 10, some areas had received More than 20 inches (53 centimeters) of rain. Credit: NWS/NOAA

Heavy storms in the South and West of the United States have led to massive flooding. Areas of Arkansas, Louisiana, Mississippi, and Texas have all experienced flash floods that began March 9. As of March 10th, parts of Arkansas had received as much as 10 inches (25 centimeters) of rain, parts of Texas got as much as 12 inches (30 centimeters), the high rain total in Arkansas was 13.5 inches (34.3 centimeters), and some parts of Louisiana were drenched with 20.97 inches (53.2 centimeters) of rain. By March 11, thousands of homes have been evacuated and five people have been killed in the flooding. Hundreds of people in Louisiana had to be rescued from floodwaters by boat and helicopter.

This situation is expected to worsen as heavy rains are predicted for these states through Saturday, March 12. On the Sabine River, which borders Texas and Louisiana, flooding is expected to reach levels not seen since 1884. Dozens of roads and interstate highways have heel closed due to flooding.

These storms come on top of severe weather in the South just a few weeks earlier. On February 18, around 20 tornadoes touched down in the Southern States. A few days later, over February 23-24, more serious storms brought more than 60 tornadoes over the two days. Unusually warm spring temperatures, which can be attributed at least in part to an El Nino, have likely fed these spring storms.

March 5, 2012

Deadly storms blew across the Midwest and South on March 2, spawning dozens of tornadoes that left at least 39 people dead amid the rubble of destroyed buildings and overturned vehicles. The storms touched down in at least a dozen states, killing 21 people in Kentucky, 13 in Indiana, 3 in Ohio, and 1 each in Alabama and Georgia. According to the National Weather Service, the four tornadoes that hit Kentucky with winds of up to 160 miles (358 kilometers) per hour were the worst in the region in 24 years. In Indiana, an EF-4 tornado–the second highest on the Fujita scale–slammed Henryville with winds of 175 miles (280 kilometers) per hour, then mowed over southeastern Indiana for more than 50 miles (80 kilometers).

The governors of Indiana, Kentucky, and Ohio have declared states of emergency. The Federal Emergency Management Agency (FEMA) announced that it was in contact with officials in the affected states. The administration of President Barack Obama issued a statement that the “extent of the damage may not be known for days” and “that the administration, through FEMA, is closely monitoring the storms and their impacts.”

A tornado's winds can swirl at speeds of hundreds of miles or kilometers per hour, hurling debris in all directions. The tornado appears in this photograph as a white funnel above a darker cloud of debris. © Gene & Karen Rhoden, Peter Arnold Images/photolibrary

The storms on March 2 were the second in the region in little more than 48 hours. The more-than 50 tornadoes in Kansas, Missouri, and Illinois on February 29 combined with the more-than 85 tornadoes that touched down on March 2 set yet another record for unseasonably severe weather in the region. In 2011, the United States experienced 14 natural disasters that each caused at least $1 billion in destruction, 7 of them involving tornadoes.

Additional World Book articles:

• Safety (During a tornado)
• Storm