Residents along Bangladesh's coast are being moved to safety as one of the strongest cyclones in years strikes the region. Millions of people had to be evacuated from low-lying regions along the Bay of Bengal on May 19. But plans are complicated by the coronavirus precautions. Maintaining social distancing is nearly impossible.

On May 14, Typhoon Vongfong slammed the Philippines with strong winds and heavy rains, destroying the city of San Policarpo in the eastern province of Samar. At least five people died and more than 91,000 people were forced to leave their homes. Typhoons are not unusual in the Philippines at this time of year. But the COVID-19 outbreak lockdown measures are exacerbating the situation.

Hurricane, typhoon, and cyclone are actually three names for the same phenomenon. Along the North American coast they are called hurricanes, in East and Southeast Asia they are called typhoons, and near India and Australia they are called cyclones. But despite the different names, they develop in the same way.

Tropical storms develop over oceans when the water temperature is at least 26 degrees Celsius (79 degrees Fahrenheit). As the warm water evaporates and condenses, the air around it heats up and drags cooler air upwards, creating powerful winds.

The Earth's rotation causes the air stream to move around the eye of the storm, which can be up to 50 kilometers wide. This area is nearly completely free of clouds and wind.

When a tropical storm hits a coastline, it becomes weaker due to the lack of warm water. In Australia, "Marcia" was soon downgraded to a category one storm, while "Lam" weakened after striking near Brisbane. Masses of water from the sea often cause the worst damage - as seen here in China after Typhoon Nanmadol in August 2011.

Hurricane Sandy was one of the strongest hurricanes ever recorded over the Atlantic Ocean. It caused waves of up to 4 meters high, fires, power outages and broken dykes. Sandy arrived with winds at speeds of more than 145 kilometers per hour. Cuba, New York and New Jersey were particularly affected.

Tornadoes however, are non-tropical whirlwinds that can occur anywhere a storm is brewing. Local temperature differences force warm air upwards and cold air down, and a column of warm air rotates upwards at an increasing velocity. Tornadoes are usually only a maximum of 1 kilometer in diameter.

As the warm air rises, it forms a funnel, the main characteristic of a tornado. Inside the funnel, the speed of the air can be tremendous - up to 500 kilometers per hour. Tornadoes are the fastest whirlwind type of weather phenomenon.

A tornado can leave a trail of destruction several kilometers long. In the US Midwest, tornadoes occur several hundred times a year, as dry, cold air from the north hits damp, warm air from the Gulf of Mexico. It's different in other countries - in Germany, for example, tornadoes occasionally occur along the coast.

Texas Governor Greg Abbott warned people ahead of landfall that Hurricane Harvey "is going to be a very major disaster." Emergency services installed surge walls on critical roads near the Gulf Coast as the hurricane gained strength before reaching land.

In a rush to prepare for the major hurricane, shoppers have emptied shelves at grocery stores. In the wake of a devastating hurricane, there can be a general lack of access to basic supplies, including food, medicine and water.

While emergency services prepared for Hurricane Harvey, others took the opportunity to surf. Ahead of major hurricanes, surfers have often taken to the rough waves before a major hurricane for a thrill ride.

Preparing for a hurricane means different things for different people. For volunteers at the Calhoun Country Humane Society, it means rushing to find homes for the remaining animals at the shelter.

Hurricane Harvey was a threatening sight as it came in from the Gulf of Mexico. The extent of Harvey is well-captured in this shot from the GOES-16 satellite.

These traffic lights in Corpus Christi shine on despite having been bowled over by the winds ahead of Hurricane Harvey. Authorities expect widespread devastation.

Seaside houses in Corpus Christi have come in for a bruising, after Harvey barreled into the Texas coast with winds of 209 kilometers per hour (130 miles per hour). But the hurricane was later downgraded from Category 4 - the second-highest - to Category 2. That still means wind speeds of up to 177 kilometers per hour, though.