Do all snowflakes have unique shapes?

Do all snowflakes have unique shapes?

Do all snowflakes have unique shapes? A snowflake from the Bentley Collection Wilson Bentley on YouTube/Weather Channel, and snowflake fun at the Why Files. It is highly unlikely that you’ll find two identical snowflakes. Feel free to try to prove… More »

How does a lake freeze?

How does a lake freeze?

How does a lake freeze? Enlarge Photo: NOAA Ice forming around the shore of Lake Michigan Lakes freeze from the top down. Ice is less dense than water, which is why ice floats. The density of liquid water is determined… More »

How does frost form?

How does frost form?

How does frost form? Heavy frost on Burr Oak tree in Wisconsin Frost on objects is just water vapor in the air that has condensed as ice onto a surface. Frost forms on objects close to the ground, such as… More »

Why does El Nino often lead to a warmer winter in Madison?

Why does El Nino often lead to a warmer winter in Madison?

Why does El Niño often lead to a warmer winter in Madison? Image: NASA Forecasts of a relatively mild winter are being tied to a phenomenon called “El Niño” in the tropical Pacific Ocean. El Niño is so often invoked… More »

Is global warming real?

Is global warming real?

Is global warming real? Image: NASA Over the past two decades, the global average surface temperature has increased noticeably. This observed warming trend indicates a significant global change and is consistent with other observed changes on our planet: There is… More »

How long have satellites been used to study Earth’s weather?

How long have satellites been used to study Earth’s weather?

How long have satellites been used to study Earth’s weather? NASA image of Explorer VII satellite, 1964 The first successful meteorological experiment conducted from a satellite was launched on Explorer VII on October 13, 1959, just over 50 years ago.… More »

What is the jet stream?

What is the jet stream?

What is the jet stream? Photo: NOAA The jet stream is a narrow current of strong wind that blows through the upper regions of the troposphere, about seven miles above ground. The jet stream generally moves from west to east,… More »

Numerical Weather Forecasting is younger than rock ‘n roll!!

Numerical Weather Forecasting is younger than rock 'n roll!!

Before 1960, the idea that a reasonably accurate two-day weather forecast could be made routinely was a pipe dream – now it’s a routine reality. In fact, it was not until just after World War I that a theory concerning the structure, life cycle and precipitation distribution associated with mid-latitude cyclones, the weather systems that bring snow and rain to Madison, was first proposed by a group of Norwegian scientists, led by Vilhelm Bjerknes, an ambitious but professionally frustrated physicist. More »

How accurate are weather forecasts?

How accurate are weather forecasts?

How accurate are weather forecasts? Image: NOAA In general, weather forecasts are getting better, due to improvements in computer models, observations and our understanding of atmospheric. Accuracy depends on the purpose of the forecast and how far out it extends.… More »

Is there a relationship between sun spots and climate?

Is there a relationship between sun spots and climate?

Is there a relationship between sun spots and climate? 12th century sunspot drawing, from NASA. Since the invention of the telescope in the 1600s, observers have recorded variations in the numbers of dark spots – “sunspots” – on the Sun’s… More »

What are heating degree-days?

What are heating degree-days?

What do heating degree-days tell us? Each degree that the mean temperature is below 65 degrees F is one heating degree-day. So if today’s average temperature is 55 degrees F, the day accounts for 10 heating degree-days. Engineers determined that… More »

What is space weather?

What is space weather?

What is space weather? Space weather describes the conditions in space that affect Earth and its technological systems. Space weather storms originate from the sun and occur in space near Earth or in the atmosphere. Space weather, like weather here… More »

What is the dewpoint temperature?

What is the dewpoint temperature?

What is the dewpoint temperature? Dew on evergreens, by Michael Theberge at NOAA Think of a morning when you walked on a grass lawn or through a field. Did your shoes get wet? If yes, that is because the grass… More »

How does weather radar work?

How does weather radar work?

A radar unit consists of a transmitter and a receiver. The transmitter emits pulses of microwaves, a type of radio waves, outward in a circular pattern. Precipitation scatters these microwaves, sending some energy back to the transmitter, where it is detected by the radar’s receiver. The intensity of this received signal, called the radar echo, indicates the intensity of the precipitation. Measuring the time it takes for the radio wave to leave the radar and return tells us how distant the storm is. The direction the radar is pointing locates the storm. More »

Why are clouds white?

Why are clouds white?

Why are clouds white? Photograph of Cumulus clouds in fair weather taken by Michael Jastremsk Clouds are made of water and clean water is clear. So why are clouds white? Because clouds are made of billions of small water droplets… More »