The temperature in Northern Virginia reached 90 degrees today. My son in Lincoln, Nebraska reported they had 7 inches of rain last Wednesday. Sunday, my friend Jim from Denver posted a picture on Facebook of his house in Denver with a couple inches of snow on house and lawn. My friend Jacque spent several days at the beach in North Carolina, but came back yesterday without a tan. This was because the weather was impacted by tropical storm Ana and there were very few rays to be had.

What else? Destructive tornadoes occurred Sunday in several states. The State of Washington declared that they are in a drought because even though they had reasonably normal rainfall during the winter, the temperatures were much warmer and the mountain snowpack on which they are depend during the summer to provide flow in their rivers and streams is much less than normal.

Wow, all this in a week! Why not? After all, its spring and spring is often characterized by weird weather.

So what is weather? Simply put, weather is the day-to-day condition at a particular place. Some of the components of weather are temperature, precipitation, barometric pressure, sunshine, relative humidity, wind, and clouds. The key words in this simple definition are "day-to-day" and "particular place." Particular place? The weather in Middleburg very likely is not the same as the weather in Virginia Beach. Conceivably, the weather in Middleburg may not be the same as the weather in Leesburg. Day-to-day? Weather can change and change rapidly. We've all experienced a bright sunny day and then, in a few hours, a drenching rain.

So how does weather differ from climate? They are not the same but are definitely related. Weather is short term and extremely variable. Climate, on the other hand, represents average weather conditions, again at a particular place, over a long period of time, for example, 50 or 100 years.

So what happens if we throw climate change into the equation?

Throughout the 4.5 billion years of Earths existence there have been monumental climate changes. As few as 10,000 years ago there were major ice sheets over at least some of the land masses in the Northern Hemisphere. Right now, we are in an interglacial period. In 1883, the volcano Krakatoa in what is now Indonesia exploded. The sound was heard 3000 miles away. The volcanic ash ejected into the atmosphere caused the average global temperature to drop by 1.2 degrees Celsius, a significant change, for the next five years. This greatly impacted climate worldwide.

Until recently, these changes have occurred without man's influence. Even now climate is changing and these changes, however subtle, and whatever their causes, have the potential to change weather patterns worldwide. Whether or not you believe as I do that carbon emissions from man-made sources are exacerbating climate change, climate change is an undisputed fact. For example, as a result of climate change, significant sea level rises are predicted during the next 50 years.

With the rapid increase in human population in the 21st century, can we cope with climate change as our numbers continue to grow? I'm cautiously optimistic that we can if we acknowledge our role in climate change. If we don't, who knows?