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Monthly Archives: October 2017
Is the Fall changing?
As we enjoyed some of the last really nice autumn weather here in Madison last week, the question arose as to whether the fall has changed in any perceptible way over the past several decades. We have reported before in … Continue reading
Is there a net loss of water from the upper atmosphere?
Yes, but very little loss occurs.
Our planet, along with all planets that have an atmosphere, lose gases to outer space. Continue reading
How does frost form?
Frost on objects is just water vapor in the air that has deposited itself as ice onto a surface. Frost forms on objects close to the ground, such as blades of grass.
At night, a blade of grass loses energy by emitting radiation (a non-lethal kind) while it gains energy by absorbing the energy emitted from surrounding objects. Under clear nighttime skies, objects near the ground emit more radiation than they receive from the sky, and so a blade of grass cools as its energy losses are greater than its energy gains. If the temperature of a grass blade gets cold enough and there is sufficient water vapor in the environment, frost will form on the grass. Continue reading
Do trees need cold weather?
Extreme cold weather can kill trees, and cold weather at the wrong time can damage trees. For example, a warm February and March in Michigan in 2012 brought early blooms to apple trees that then were killed by an April frost.
Some trees require cool temperatures, such as some fruit trees (peaches, cherries and blueberries) and nuts (almonds). Cold air along with less sunlight that comes with winter halts tree growth, preparing the tree to withstand freezing temperatures and then resume their growing the following spring. Continue reading
